A woman living in a tent nearby, Umm Mohammed Bakrun, said she had been talking to her son when the building collapsed suddenly in the early hours of Wednesday.

“It felt like an earthquake. There was a loud sound and I couldn’t stand up. Stones rained down on us and when I looked outside I saw a lot of dust,” she told the BBC. “Within minutes, there were screams everywhere.”

Another witness, Mansour Abu Mohammed, said the building collapsed “in a few seconds”.

“Every day, a stone or a few stones would fall from it, but the people inside couldn’t find anywhere else to live. I used to live next door to it and you could see that it was tilting to one side.”

Locals said some 10 families had been living in the building’s apartments.

The head of the United Nations Development Programme (UNDP) Gaza office, Alessandro Mrakic, told reporters at the scene that between 70 and 100 people were believed to be trapped under the rubble.

“The situation, as you see, is tragic because we don’t have the equipment and machinery that is needed. There are actually people digging with their bare hands,” he said.

Mrakic also warned that approximately 400 other war-damaged buildings across Gaza were at imminent risk of collapse, particularly as winter approaches.

“We need support, most importantly with machinery, equipment, among others. Our colleagues here don’t have [engine] oil and spare parts to continue to work with all the equipment that is still in Gaza.”

The UN’s humanitarian relief co-ordinator, Ramiz Alakbarov, said he was “devastated” by the reports of the building collapse.

“No-one should have to risk their life simply to find a safe place to shelter,” he said.

He also urged Israeli authorities to approve deliveries to Gaza of heavy machinery for rescue operations, as well as tents, tarpaulins and other non-food items for displaced people ahead of the winter rains.

Israel says its restrictions are meant to keep equipment out of the hands of Palestinian armed groups that could also have military uses.