Dozens of displaced Gaza families flooded into a UN school early Tuesday after Israel warned them to leave their homes, struggling to set up camp in a cramped, dirty courtyard.

Hundreds of homeless Gazans were already living there, with this school in the northern town of Jabaliya packed to overflowing.

Rubbish piled up outside the school walls, filling the air with a foul stench, as women used brooms and muddy water to clean up their new accommodation — festering classrooms packed with dirty mattresses and bedclothes.

“The army simply told us: You must leave the area now. Those who don’t are entirely responsible for their own lives,” said Ghassan Abed, who fled his home in the nearby town of Beit Lahiya the night before.

The warning was sent by text message and automated voice calls to hundreds of thousands of people living in the northern areas of Beit Lahiya, Beit Hanun and Jabaliya, as well as to those living in Zeitun and Shejaiya to the south and east of Gaza City.

Similar messages sent to other districts earlier this month sent more than 200,000 people fleeing for safety, UN figures show.

“The messages said to go to Gaza City, but it’s not that simple — we’ve no relatives there and nowhere to stay,” said the 46-year-old who is a Palestinian Authority policeman and father of six.

Abed said some 200 to 300 people from his street alone had simply packed up and left — terrified of getting swept up in violence that has killed more than 1,100 people, mostly civilians, and razed entire neighbourhoods across the tiny coastal territory.

“Almost the whole of Beit Lahiya has come here. There are no rooms left. People are having to live in yards,” said Samer Kilani, from Beit Hanun.

With several families to a classroom, the displaced have overflowed in corridors and out into the courtyard, where mothers hang blankets from awnings, trying to create some shade from the scorching sun.

One woman uses an old dress as a doormat for the entrance to her new home, as children wander past barefoot.

“It’s not a clean, healthy environment,” said Abed.

“The kids are getting sick from lack of clean drinking water. There’s only a small supply, so most people haven’t washed for days.”

And food supplies are becoming short.

Muna Abu Amsha, a mother in her 40s, holds up a piece of stale bread.

“We want to eat, but nothing’s fresh,” she said, as her toddler daughter licked clean a plastic plate of raw vegetables.

An aid truck arrived to deliver bread, but not much — just a few dozen small bags.

The Abu Amsha family — all 20 of them — have been in the school for around two weeks after fleeing Beit Hanun earlier in the bloody 22-day conflict.

Israel’s army has blamed Hamas for civilian deaths, saying its fighters deliberately hide in residential areas, turning them into “human shields”.

The army admitted shelling a UN school in nearby Beit Hanun on Thursday, in an incident medics said killed 15 people.

The military says the school was empty at the time, but Palestinian refugee agency UNRWA insists it was still being used as a shelter by hundreds of people.

UNRWA says it is currently sheltering 182,604 displaced Gazans who are staying in 83 of its schools, which sometimes have to be vacated for security reasons.

And given the ongoing fighting, delivering food to the displaced can be “particularly difficult”, agency spokesman Christopher Gunness told AFP.

A short distance away, several explosions ring out, scaring the children.

Abed had no idea how long the family would be camping out at the school.

“It depends on the political situation. There needs to be agreement on a truce. But there’s no sight of that.”

The gravity of the situation is not lost his 13-year-old son, Mohammed.

“It’s really difficult here, we’re uncomfortable away from home,” he said.

“I want to go home, but there’s no safe place now.” SAPA