JOHN YANG: Good evening.

I'm John Yang.

Israeli forces are now carrying out ground operations in Gaza after days of bombardment from the air.

Israel is trying to pressure Hamas to free the remaining hostages.

Overnight, Israeli strikes across southern Gaza killed 26 people, including several women and children.

A senior leader of the political wing of Hamas is among the dead.

In Rafah, Israel ordered residents to evacuate as its ground forces moved into the city.

AMAL NASSAR, Diplaced Gazan (through translator): The shells are falling among us and the bullets are flying above us.

Injuries, killings, all the streets have filled up with people and children.

Where will we go?

How long will we remain in this suffering?

We have children.

Shame on them.

JOHN YANG: The Hamas run Gaza Health Ministry says the death toll in the 18 months since the war began has surpassed 50,000, nearly 700 of them since the ceasefire collapsed this past week.

Earlier, I spoke with UNICEF spokesperson Rosalia Bollen from Gaza.

ROSALIA BOLLEN, Spokesperson, UNICEF: The situation here continues really to deteriorate day by Day.

Since March 18, there have been hundreds of people killed, including at least 200 children, hundreds of children, more injured, including children with very severe injuries, burns all over their body.

And those attacks have been accompanied by displacement orders for notably northern Gaza, eastern Gaza and the south.

So families have been told to move yet again.

The vast majority of families had just returned to their homes a couple of weeks ago during the ceasefire, and now they're pushed out again and they are in urgent need of food assistance, clean water support with shelter.

We also have been facing an aid blockade since the beginning of March.

For three weeks now, UNICEF and other organizations, we haven't been able to pick up the life-saving assistance that we have right outside of Gaza.

I've been here for six months now, but when I drive around, I continue to be overwhelmed by just the sheer scale of devastation and destruction.

Like some areas look like a moon landscape with large craters.

Not a single building that is still standing.

It's rubble mixed with sand, debris, solid waste.

Everywhere you look, children live in the midst of the debris of the rubble.

There's unexploded ordnance, so there's bombs that have been dropped but that haven't gone off.

So it's a very dangerous place to be.

And children haven't been allowed to be children.

They're no longer children inside Gaza because of the exposure to violence, because they have to help their parents every day to survive.

It's become evident that every child in Gaza today is deeply traumatized, scarred and in need of urgent support, including mental help.

JOHN YANG: Had conditions been getting any better during the ceasefire before it broke down, before the aid blockade was put back in place?

ROSALIA BOLLEN: Yes.

So during the first six weeks of the ceasefire, we actually have been able not just to bring in considerably more life-saving assistance, but we have also been able to reach families throughout Gaza, wherever they were, and families had been able to move freely as well.

Unfortunately, we haven't been able to perform any miracles.

We're a couple of hundreds of humanitarian workers here inside Gaza, but the scale of devastation in Gaza is just impossible to undo.

Over a couple of weeks of times, we haven't been able to do any major rubble clearance to start rebuilding Gaza.

We've just been distributing as fast as we could this life saving assistance.

We've really been racing against the clock.

And we want to assist the population and we're ready to do that, but we need to be able to access our supplies.

JOHN YANG: The children and the families you've been dealing with, particularly in the last week, are there any that sort of stand out in your mind?

ROSALIA BOLLEN: The children I interviewed and the stories that I recorded made it evident that children were very acutely aware of the importance of the ceasefire negotiations.

They know the names of the countries who are involved, they're asking questions and they're talking about all the things that they want to do.

The moment that the ceasefire is there.

It's just shattering really, to see that the fighting and the attacks have restarted.

JOHN YANG: UNICEF's Rosalia Bollen in Gaza, thank you very much and please stay safe.

ROSALIA BOLLEN: Thanks for having me.