Tonight, several developing stories as we come on the air. The fallout after Israel and Hezbollah launch major attacks against each other. 50 million Americans under heat alerts and flash flooding at the Grand Canyon with multiple rescues and the search for a missing hiker. First, the major escalation in the Middle East. Israel launching a wave of airstrikes on Hezbollah, saying the militant group was planning an extensive attack. Hezbollah firing back on Israel with drones and rockets. Tonight, the tension is easing, but two US aircraft carriers have been ordered to remain in the region. What it could mean for hopes for a ceasefire in Gaza as talks continue. Our team following the latest developments. Also, tonight, the late summer scorcher, 50 million Americans under heat alerts from the Great Plains to the Upper Midwest. The heat expected to fuel severe storms as the work week begins. Flash flooding at the Grand Canyon. The National Guard called in to rescue hikers, and the search continues for a woman swept left away in the floodwaters. The race for the White House kicking into high gear. Vice President Harris heading to the critical state of Georgia, as her campaign reports it's raised more than a half billion dollars since she declared her candidacy.

Former President Trump hitting three battleground states. Empty parks and a warning to stay indoors after dark. Several towns sounding the alarm about a rare but potentially deadly virus spread by mosquitoes. Misstery surrounds the arrest of a billionaire CEO, the founder of the messaging service Telegram, reportedly taken into custody in Paris. Growing tension as ships collide in the South China Sea, China and the Philippines blaming each other for the confrontation in a vital trade route. Record auction. A jersey once worn by Babe Ruth sets a new record for sports memorabilia. And Standing Tall, a statue honoring a civil rights icon, replaces a symbol of division.

From ABC News, World headquarters in New York.

This is World News Tonight. Good evening. Thank you for joining us on this busy Sunday. I'm Mary Bruce in for Lindsay Davis. Tonight, fears of a wider war in the Middle East appear to be subsiding for now, with both Israel and Hezbollah declaring victory in the largest cross-border attacks against each other since the start of the war in Gaza. Overnight, Israel firing first, launching what it called a preemptive strike against Hezbollah in Lebanon, saying the militant group was planning an extensive attack. Hezbollah did fire back with a barrage of missiles and drones toward Israel, saying it was retaliating for the killing of a senior commander in Beirut last month. The US making it clear it was not involved. But late today, Defense Secretary Lloyd Austin ordered the two US aircraft carriers now in the region to remain there. Tensions are still high tonight. Iran has also vowed retribution for the killing of a Hamas leader. What does it all mean for those ceasefire talks. Abc's Brit Planet leads us off from Tel Aviv.

Israel and Hezbollah unleashing their heaviest exchange of fire after months of tit for tat fighting. But tonight, the two now seeming to back away from all-out war. Israel saying they launched preemptive strikes involving 100 planes to take out thousands of rocket launches and missiles in Southern Lebanon after detecting plans for an attack on its soil. The IDF saying it struck over 40 sites. The Iranian-backed militia firing at least 320 rockets into Israeli territory. The Israeli military saying most of the intended targets were in Northern Israel, but some in Central Israel. Sources telling ABC News those targets were estimated to be intelligence bases and the headquarters of Israel's main spy agency, Mossad, just north of Tel Aviv. Hezbollah's leader, Hassan Nasrallah, tonight saying the group's latest operation was completed, but that they will wait and see if more action is needed. The strikes in retaliation for the Israeli assassination of its military commander in Beirut three weeks ago. Israeli Prime Minister, Benjamin Netanyahu, saying drones were in deceptive that were trying to reach strategic sites in central Israel. Adding that this is not the end of the story. Just today, we're learning while the US was not involved in those strikes, they assisted the IDF in tracking incoming attacks.

The US ready to defend Israel, the Pentagon ordering the two aircraft carrier strike groups to remain in the region. The Middle East remaining on edge tonight. The US Embassy in Beirut telling citizens to prepare contingency plans and be prepared to shelter in place. Amid fears of a wider war, ceasefire talks to and then the fighting in Gaza, once again collapsing, with Hamas saying it does not accept the latest iteration of the deal because of new conditions added by Israel which cross its red lines, including Netanyahu's insistence on a military presence in Gaza. More evacuation orders in the humanitarian zone in Deir Al Bala, the fighting closing in on Gazan mother, Arwa Naïf, who says leaders don't take their suffering into account.

We, people on the ground, we are not among the calculations of any of these parties. All this coming as the suffering continues there in Gaza. Brit Kleinet joins us now from Tel Aviv. And Brit, both sides have signaled they're backing off for now. But Israel says they stand ready for what's next.

Yeah, Mary, even after the escalation we saw this morning, both sides are indicating they won't back down. The IDF tonight saying it remains at a very high level of readiness to attack and defend in all arenas.

Mary. Brit Kleinet tracking it all from Tel Aviv. Brit, thank you. The White House says President Biden is closely monitoring the situation in Israel and Lebanon. But one US official tells ABC News the US was not involved in the Israeli operation. So let's bring in ABC's Mary Alice Parks, who joins us now from the White House. So Mary Alice, what more are you hearing?

Yeah, that's right, Mary. We're told the US was not involved in any military operation, but did provide intelligence and surveillance. Look, US officials seem to be breathing a sigh of relief. We know the President has been getting updates from his national security team today, but they also had intelligence that Hezbollah was planning this extensive attack. It seems that Israel was able to undercut that and defend itself. Earlier this month, the Pentagon rushed significant military assets to the region, including that second carrier strike group with four accompanying destroyers. There's also a squadron of F-22 fighter jets in Qatar. All of this to try to deter any further escalation from Iran or its proxies. We are now told that both of those strike groups will stay in the region. There is still real concern about whether Iran could also be planning its own retaliatory strikes for that Hamas leader that was killed in Tehran. Now, Mary, as far as those ceasefire talks around Gaza, the White House telling me today that they still think the meetings were constructive, even if Hamas rejected that latest proposal. Whistle, but of course, a lot of questions about what will possibly move the ball forward at this point.

Mary. All eyes on those talks, but still no breakthrough. Mary Alice, thank you. Now to an urgent search for an Arizona hiker swept away by flash flooding in the Grand Canyon. Thunderstorms They're forcing rivers over their banks. Arizona's governor calling in the National Guard to help rescue more than 100 people. Here's ABC's Jacquelyn Lee.

Tonight, the frantic search for 33-year-old Chinoa Nickerson swept away in a flash flood while hiking at the bottom of the Grand Canyon in Arizona. Other hikers in the area capturing the speed of those floodwaters. The region in the midst of monsoon season when showers and thunderstorms frequently pop up. The power of the water comes out of nowhere. La Trisha Mims, part of a group that made it to higher ground, evacuated by helicopter. We made it out with probably 40 or 50 of us stuck together and helped each other cross the water. The state's governor activating the National Guard to aid in rescue efforts, bringing more than 100 tourists and members of an Indian tribe to safety. This as record-breaking heat has gripped the Southwest this summer. National Park official's warning of the risks as temperature soar. We saw firsthand how the Grand Canyon's search and rescue teams prepare to deploy amid multiple fatalities this summer. What is the most critical aspect of search and rescue? Timing.

It is really key to it. The quicker we know that somebody is needing help, the quicker we We can respond and mobilize and make that happen.

And tonight, about 25 National Park Service personnel are assigned to the search for Chinua Nickerson, with one helicopter and two rescue vessels involved. Mary, officials say they're focusing their search on the Colorado River and have a Creek.

Mary. Okay, Jacquelyn, thank you. So let's bring in ABC meteorologist Samara Theodore. Samara, you're tracking even more severe weather and a heatwave impacting more than 50 million.

That's right, Mary. For the start of the work week, the central portion of the country is in for a scorcher. Take a look at this. Heat Advisory stretching all the way from Northern Texas up to Fargo. Excessive heat warnings for places like Chicago. Headed back to work in Chicago. Temperatures will be heating in the upper '90s. Potentially record-breaking heat Monday and Tuesday. A lot of places feeling like 112. And this heat only exacerbating the situation, fueling these storms that are moving through the upper Midwest. They stand to see an enhanced risk for severe storms. A few tornadoes are possible in places like Sioux Falls and Minneapolis. And we can see that threat shift farther east to the Great Lakes by Tuesday. Mary?

A wild start to the week for so many. Samara, thank you. We turn here now to the Race for the White House. With 71 days to go, both vice President Harris and former President Trump are focusing on the critical swing states that could decide the election. Harris and Walls are in Georgia this week with a bus trip through that key state, while Trump heads to Michigan, Wisconsin, and Pennsylvania. Here's ABC's MWin.

Tonight, 71 days until election Today, Kamala Harris's campaign touting a fundraising surge. $82 million dollars raised last week during the Democratic National Convention. More than half a billion dollars total since the vice President launched her campaign last month. This week, both tickets hitting the campaign trail, zeroing in on battleground states that could determine the election. Harrison running late Governor Tim Walls taking a bus tour across Georgia, while former President Donald Trump set to Barnstorm, Michigan, Wisconsin, and Pennsylvania. Harris now leading in each of those states, with the exception of Georgia, according to the 538 polling averages. Republican vice presidential nominee Senator JD Vance, heading to Michigan this week, press today on the prospect of a national abortion ban. If such a piece of legislation landed on Donald Trump's desk, would he veto it?

I think it'd be very clear he would not support it. He said that explicitly. But would he veto it? Yeah. If you're not supporting it as the President of the United States, you fundamentally have to veto it. So he would veto a federal abortion ban? I think he He said that explicitly that he would.

Senator Elizabeth Warren, set to campaign in Wisconsin for Harris this week, pouncing.

American women are not stupid, and we are not going to trust the futures of our daughters and granddaughters to two men who have openly bragged about blocking access to abortion for women all across this country.

And Mary, this election may come down to those who are still on the fence. Our latest polling and analysis by ABC News, The Washington Post and Ipso shows about 12% of Americans are still open to changing their minds about who to vote for or whether they'll vote at all. Mary?

Seventy-one days to go. Okay, Em, thank you. Towns and cities across the country are now on alert for mosquito-borne illnesses, including the rare Eastern equine encephalitis virus. Plymouth, Massachusetts, is closing parks and fields at dusk. Other towns are urging people to avoid going outdoors at night during those hours of peak mosquito activity. More now from ABC's Aika Jachi.

Tonight, during the final weeks of summer, Plymouth, Massachusetts, south of Boston, closing its parks and fields from dusk till dawn. One of 10 communities in the state where families are at high or critical risk for becoming infected with the Eastern Equine Encephalitis virus, a rare but potentially deadly mosquito-borne illness.

Key thing is there's no vaccines or treatment for triple E, so prevention is really very critical.

Starting this week, crews will spray for mosquitoes from the ground and from the air in more than a dozen towns. The CDC says, although most people who get the triple E virus have no symptoms, a small percentage develop brain inflammation, and about a third of those people will die, and many survivors suffer long-term neurologic damage. In 2019, the threat of the triple E virus impacted Friday night lights in multiple states. Let's go Connecticut's Windsor High School, among those rescheduling their football games and other outdoor activities to before dusk to limit exposure to mosquitoes. That year, there were more than three dozen cases of human triple E virus across 10 states in the US. The highest on record, at least 12 people died. And in New York City, crews spraying in Manhattan and Brooklyn this week to combat another mosquito-borne illness, the West Nile virus. Dr. Anthony Fauci, among those in the US, now recovering from that virus. Mary, officials say be vigilant about practicing protective behaviors. Use repellents with EPA-registered active ingredients. When outdoors, wear clothing that covers the skin and reschedule outdoor activities to avoid the hours between dusk and dawn. Mary?

Okay, some good advice there, Ike. Thank you. The Port of Seattle says it is working to restore Internet and web service, knocked out by an alleged cyber attack. Officials say the outage is affecting some systems at the airport. Abc's Morgan Norwood joins with us now. Morgan, what's the latest?

Hi, Mary. Yes, authorities still scrambling to get those systems back online and trying to figure out who is behind this cyber attack. That authorities say brought down critical systems over at Seattle Tacoma International Airport. Tonight, though, operations looking much better here. A big improvement from Saturday when more than 350 flights were delayed. The minor meltdown, well, that's going to be a major test ahead of what will likely be a record-breaking Labor Day Travel Week. Tsa is expecting to screen more than 17 million passengers between this Thursday and next Wednesday. That is up 8.5% from last year. As for this alleged cyber attack over in Seattle, authorities are still investigating, but no timetable yet on when systems will return to normal. Mary.

Okay, Morgan, thank you. German authorities say a man in custody in a fatal stabbing attack is strongly suspected of being a member of the terrorist group, ISIS. The 26-year-old Syrian National is accused of three counts of murder and eight counts of attempted murder in Friday's incident at a festival in the western part of the country. Two others have been detained but have not been charged. There is still much more ahead here on World News tonight this Sunday, including the mystery surrounding the arrest of a billionaire CEO and escalating tensions in a key shipping lane with ships ramming into each other. Next, tonight, the founder and CEO of the popular messaging platform, Telegram, has reportedly been arrested in France. According to French media, Pauvre Dura, Duraal was detained on a warrant that alleges the messaging service is being used for various crimes, including online sexual exploitation and money laundering. Telegram, which is widely used in Europe, says Duraal has nothing to hide and that the company abides by all EU laws. Tensions between China and the Philippines are escalating tonight. Both countries are accusing the other of hitting each other's ships in the South China Sea.

These images here put out by the Philippine government show a Chinese vessel ramming a Filipino ship. It is the second incident involving the two countries in as many days. On Saturday, the Philippines accused China of deploying flares near one of its aircraft that was out on patrol. When we come back, the baseball jersey that sold for an eye-popping price. To the index now for one officer, it was all in a day's work. Fulcher, Texas Police Lieutenant Bill Henry got the call about a small alligator that showed up at a resident's front door this week. Henry, though, didn't hesitate grabbing the gator with his bare hands there. It put up quite a fight, but the lieutenant held on and took it away. Turns out that was actually his second gator call of the day. A piece of baseball history was sold for an astronomical price overnight. Someone paid more than $24 million for the jersey worn by Yankees legend Babe Ruth, when he famously called his shot before hitting that home run in the 1932 World Series. Heritage Auctions did not identify the buyer, but that person now owns the most expensive sports collectible in history.

Now to an instant classic. Congratulations tonight to the team from Lake Mary, Florida, just taking the Little League World Series. Hunter Alexander's bunt in the eighth inning led to the winning run. Lake Mary beat Taiwan 2-1, and the celebration there was on. Lake Mary coming from behind to win each of its last two games, a very well-earned Championship. When we come back, the new tribute to a civil rights icon. Finally, tonight, a symbol of unity replacing a symbol of division. For over a century, a Confederate monument loomed over this historic square in Decatur, Georgia. But now, tonight, in its place, stands tall, a champion for equality. Civil rights icon, late congressman John Lewis. I'm 82 years old, so I have seen a lot, and this is really good for us, and we going to enjoy. The unveiling yesterday, spark cheers and joy. The moment, the culmination of a years long plan to honor the hero who died in 2020. Louis was one of the original Freedom Riders. He helped organize the march on Washington and was brutally beaten while peacefully marching across the Edmund Pettus Bridge on what became known as Bloody Sunday. Well, once existed a monument to bigotry and hatred is being replaced by one of brotherhood and love I'm in peace.

Louis now memorialized in the 12-foot tall bronze statue, his hands over his heart, his eyes closed. A fitting pose for the man who inspired so many, urging the next generation to get in, quote, good trouble necessary trouble.

I just hope the young people who are going to be walking by to going to school every day in the city appreciate and understand his legacy and find a way to make good trouble.

Necessary trouble. Thank you for watching. I'm Mary Bruce. Good night.

Thank you for making World News Tonight with David Muir, America's most watched newscast.