JOHN YANG: Good evening.

I'm John Yang.

Overnight, Israel carried out the heaviest bombardment of Beirut in its air campaign against Hezbollah.

Massive explosions lit up the skies, and plumes of thick smoke covered the city.

Civilians had been warned to evacuate their homes.

They returned to ash and rubble.

DENISE MATRA, Displaced Resident (through translator): Let all the countries talk to them and put pressure on them to stop the war and negotiate with each other.

Let them deal with it.

What is the fault of the people and those children who died?

They left us with nothing, and we have become nothing.

JOHN YANG: Nearly a quarter of the Lebanese population has been displaced in Beirut.

Some live out of their cars or tents.

Special correspondent Leila Molana-Allen is in Beirut tonight.

Leila, the Israelis have intensified both the scope and the intensity of their bombardment of Hezbollah in Lebanon.

Where is a sense of the, where this goes from here?

LEILA MOLANA-ALLEN: They have.

And what's really been clear over the last few days is just how much that bombardment has intensified.

A week ago, we were looking at certainly in and around Beirut, a few strikes a day, and there were regularly warnings for those.

That's really changed now.

Last night was by far the most intense bombardment we've experienced here, at least 25 to 30 strikes throughout the night, incredibly intense strikes, shaking the whole city and flattening buildings across the suburbs of Beirut, but also further as well.

Many, many people now packing up and running for their lives.

Now in the south of Lebanon, where they've been hitting harder and harder, initially what were hearing was there was going to be bombardment of those southern villages south of the Litani River, which is where the IDF wants Hezbollah to withdraw to.

We initially saw that and those ground raids as well.

But that zone has spread significantly.

We're now seeing evacuation orders for cities all the way up the south of Lebanon, major population zones, people streaming up the border to try and get out of those areas.

And really a lot of those southern towns have now been flattened with seeing quite incredible destruction of those buildings.

What's also happening, of course, in this fight is that the IDF is sending troops into the south of Lebanon to fight with Hezbollah troops on the border.

They say, the IDF, that they managed to clear 250 meters of subterranean tunnels used for transporting weapons over the last couple of days.

They've managed to seal those with concrete.

And there's also heavy fighting happening on the ground.

At least eight IDF soldiers have been killed.

Hezbollah says they have killed many more.

The IDF hasn't confirmed those yet, but we're certainly seeing heavy fighting down there.

JOHN YANG: You talk about people packing up and running for their lives.

The head of the U.N. refugee agency has said that there is a major displacement crisis in Lebanon.

Now talk about that.

LEILA MOLANA-ALLEN: Well, as you said, John, at least 1.2 million people have been displaced.

That is a quarter of the population of Lebanon.

And what we're seeing with this displacement, of course, we know that at least 60,000 residents from the north of Israel have been displaced for nearly a year now because of those Hezbollah rocket attacks.

But on the other side of the border, there isn't the capacity to house these people.

Here in Lebanon, there's been a major financial crisis, which I've, of course, reported on for the NewsHour for five years here.

The government is in complete disarray.

There's no president.

There's been no prime minister.

There's been no government for two and a half years.

So they're not in a position to handle this.

Every morning you see more and more people spread out across the streets of the Capitol, across the streets of the central southern towns.

They are sleeping on mattresses.

They're sleeping on blankets, small children in the baking heat.

It's pouring rain at night.

They've escaped with really just plastic bags full of whatever they could carry.

There have been some shelters that have been opened, some by the municipalities and a lot by local charities, but they just don't have the capacity.

People are finding many of those shelters closed, and of course, all that money is just coming from local charities.

We're seeing an enormous scale of human misery here.

And when these Israeli evacuation orders come out, people say, well, of course, why don't they just clear leave to save their lives?

They really have nowhere to go.

They have short notice, but they really also just have nowhere safe where they believe they can be.

They don't have the money for this.

They don't have food.

They don't have medicine.

They don't have proper shelter.

So we're seeing an incredible crisis spreading out across the streets of Lebanon here.

And just a reminder that, firstly, there are no air raid sirens or bomb shelters in Lebanon.

So when people are running from these bombs, they are running out in the streets and taking shelter wherever they can.

And secondly, most people in Lebanon who are left here who have not managed to evacuate yet don't have foreign passports, don't have visas, they can't get out of the country.

They are stuck here.

JOHN YANG: And in cases like this, there's also governments, foreign governments trying to get their citizens out of the country.

How is that going?

LEILA MOLANA-ALLEN: So for many months now, western governments and particularly the United States government and the U.K. government have been warning citizens, you should leave.

Please get out while you still can.

Please get out while there are commercial options.

There have been warnings that this crisis was going to escalate.

Now the United States says that they have managed to evacuate, help and assist 500 us citizens in the last couple of weeks.

They ran a flight on October 4 where they managed to get 150 further people out.

That was a flight that they ran themselves and they say they've assisted nearly 2000 people over the last few weeks with sea on commercial flights.

Now we are reaching a point where those evacuation options are becoming much more difficult.

There have been military flights for multiple western countries that are flying people out.

But the issue here is that right now the only airline flying in and out of Beirut airport is the national carrier, Middle East Airlines.

All other airlines have ceased to fly and they are flying through smoke.

They're flying through shards of bomb fragments when they land at that airport.

Because just to give you a sense of how close we are to these explosions, Beirut is only about 13 miles square, the center of the city and about 40 miles squared, the whole of the wider city, including the suburbs.

That airport is right next to these southern suburbs that are being bombarded every hour of the day.

So that's what people have to get through.

One of the roads, the old road to the airport, was hit yesterday.

The main highway is still open.

The airport's still functioning, but we don't know for how long.

In 2006, when the war happened, Israel did hit that airport and put it out of commission.

And because the two borders here are with Israel and with Syria, crossing them is not an option for most people.

So we may soon see military aircraft carriers and speedboats coming and taking people to Cyprus and to Turkey from the ports here.

That's the fear that we could be seeing a mass evacuation by sea for anybody who hasn't left yet.

JOHN YANG: The U.S. State Department said that they are working to get a ceasefire in Lebanon.

Of course, they've been trying to get a ceasefire in Gaza for months without much success.

What do you think the chances are of success here?

LEILA MOLANA-ALLEN: There seems at the moment very little chance of a ceasefire.

What we're seeing here, of course, is with the October 7 anniversary coming up tomorrow, huge tensions across the region.

Everybody is expecting some significant attacks on both sides of the border and of course, everybody also waiting for what Israel's response will be to Iran's huge missile attack on the country earlier this week.

The United States and other allies of Israel have urged them not to target Iran's nuclear facilities or any major infrastructure to try not to escalate.

But what we've really seen happening is Israel increasingly not listening to its western allies saying, we are now in this position where we need to defend ourselves and we will do whatever is necessary.

Israel says that this fight is against Hezbollah, but much of the infrastructure they're hitting, we are seeing huge civilian high rises being hit.

We're seeing medical infrastructure being hit.

100 medics, at least, have been killed in just the last couple of weeks.

There were 28 medics killed here in 24 hours.

Not just hospitals, which are being struck, but also ambulances, civil defense going and trying to dig civilians out of buildings.

That forms a part of the larger issue here, which is that not only have things become so polarized in this region, one side or another, but in the rest of the world across the west, people have such incredibly strong feelings on either side about this conflict.

And what we've seen is the complete dehumanization of civilians on both sides of this conflict, whichever side it is that one supports and a real lack of what used to be the fundamental principle here, that civilians must be protected in all cases.

People here are absolutely terrified that they feel no one in the international community is understanding the extent to which civilians are being affected by this escalating conflict, and they just see that getting worse and worse.

There's real fear across the region now that this could turn into an absolutely brutal, all-out war in which hundreds of thousands of lives are affected forever.

JOHN YANG: Leila Molana-Allen in Beirut tonight.

Thank you very much.