Adham Bartawi had hoped for the best when he set off back to his family home in the north of Gaza after more than a year – but he was shocked at what he found.

“Half our house is gone,” the 31-year-old told the BBC from the ruins of where he used to live in the northern city of al-Zahra.

“It looks like it was bulldozed – the living room is gone, the kitchen is gone, most of it is gone. The only thing remaining is two rooms and one bathroom… If I leave now they might be looted,” he said.

Adham is one of the hundreds of thousands of Palestinians who have made it back to the north since Israel allowed displaced residents to start to return on Monday.

The return is a result of the ceasefire deal between Hamas and Israel that is aimed at permanently ending the war that began when Hamas attacked Israel on 7 October 2023.

A United Nations official told the BBC there was a “massive, massive effort ahead” to ensure that key services were provided to those returning north.

One man who had returned to his home in Jabalia told the BBC it was “not possible to describe” the destruction around him.

“You’re speaking to me while I’m clearing a space to put up a tent… We are trying to manage ourselves and find a way to live here,” 48-year-old Imad Ali al-Zain said over the phone.

“I was happy and chanting on the way back, but when I reached my home I was disappointed because of the disastrous scene in front of me. I wished I’d never come.”

The UN estimates that about 70% of the Gaza Strip’s buildings have been damaged or destroyed since October 2023, with much of the worst destruction in the north.

Sam Rose, acting director of the UN agency for Palestinian refugees (Unrwa) in Gaza, told the BBC the population in northern Gaza would likely “be doubling in the next few days”.

“What they’re going back to, many of them, are scenes of complete devastation. They know before they travel that their homes are likely to be destroyed or severely damaged, but they want to go home anyway,” he said.

“Since the ceasefire came into effect a week ago, basic aid supplies have been coming in, so we’re able to provide food, some water, basic shelter supplies, some monitoring of particularly vulnerable cases. But it’s a massive, massive effort ahead of us.”

Many more people are preparing to make the journey from south to north in the coming days, by foot or vehicle.

Ihab Qraqeh, a telecoms worker who has been displaced since mid-October 2023, said he had waited to see how the first day of the return unfolded before setting off himself.

“We sent some of our family members yesterday and now we are planning to go. We are waiting for the car to come so we can start packing and go,” he said.

A man the BBC had spoken to on Monday who was preparing for the journey with his heavily pregnant wife said they had set off but turned back around.

“It was too difficult for us. I was afraid that she would suffer complications. She’s eight months pregnant. So we came back [to wait at a relative’s home in central Gaza],” said Khalil Shabeer, 32.

“Even using a car, the road feels infinite – the line of cars is endless when you look at it.”

Additional reporting by Muath al-Khatib