At least 28 Palestinians, including children, have been killed in an Israeli strike on yet another school-turned-shelter in the northern Gaza Strip, a health official has said, as Israeli forces press on with their ground assault in the area.

Thursday’s attack on the ravaged area, which has been besieged for nearly two weeks following a renewed Israeli ground offesnsive, wounded 160 others, according to Palestinian health official, Medhat Abbas.

“There is no water to extinguish the fire. There is nothing. This is a massacre,” Abbas said. “Civilians and children are being killed, burned under fire.”

The Israeli military, without substantial evidence, said the strike targeted fighters from Hamas and the Palestinian Islamic Jihad groups. It claimed the fighters operated from within the Abu Hussein School in Jabalia that had been serving as a shelter for displaced people.

Hamas strongly denied the claim that it was using the UN agency for Palestinian refugees (UNRWA)-run school for fighting purposes and said in a statement that the allegations were “nothing but lies”, adding this was “a systematic policy of the enemy to justify its crime”.

Earlier on Thursday, Palestinian health officials said at least 11 Palestinians were killed in two separate Israeli strikes in Gaza City, while several others were killed in central and southern Gaza areas.

Footage circulated by Palestinian media of the Abu Hussein School showed smoke coming from tents that caught fire, as many displaced people evacuated casualties, including children, to ambulances.

Residents of Jabalia said Israeli forces blew up clusters of houses by firing from the air, from tanks, and by placing bombs in buildings and detonating them remotely.

The area has been a focus for the Israeli military for the past two weeks. The UN estimates that some 400,000 people are trapped in northern Gaza and have been unable to leave due to intense bombardment, Israeli snipers, and ground troops.

Since the latest incursion, northern Gaza, including Beit Lahiya and Beit Hanoon, has been completely sealed off. Israeli troops have cut off the region allowing in no food, drink, or medicine. Local officials say people are starving.

Doctors at the Kamal Adwan, al-Awda and Indonesian hospitals have called for a humanitarian corridor and have refused to leave their patients despite evacuation orders issued by the Israeli military.

‘Punishing us’

Al Jazeera’s Hani Mahmoud, reporting from central Gaza’s Deir el-Balah, said the scene at the Kamal Adwan Hospital following the latest attack is “horrific”.

“The casualties were picked up on carts pulled by animals or civilian vehicles at the bomb site, arrived at Kamal Adwan Hospital, and are on the floor of the emergency department,” Mahmoud said.

“The scene is horrific. They can’t keep up with the large influx of casualties coming to the hospital.”

Thursday’s attack was the latest in a string of Israeli strikes on school buildings housing displaced Palestinians in Gaza.

The attacks have predominantly killed children and women. Many of the schools run by UNRWA have also been damaged or destroyed.

Calls for evacuation have meanwhile fueled fears among Palestinians that the drive is aimed at clearing them from northern Gaza permanently.

“We have written our death notes, and we are not leaving Jabalia,” one resident told Reuters news agency.

“The occupation is punishing us for not leaving our houses in the early days of the war, and we are not going now either. They are blowing up houses, and roads, and are starving us but we die once and we don’t lose our pride,” the father of four said, refusing to give his name, fearing reprisal.

Northern Gaza, which had been home to more than half of the territory’s 2.3 million people, was reduced to rubble by bombing in the first phase of Israel’s assault on the territory a year ago.

More than 42,000 Palestinians have been killed in Israel’s ongoing offensive so far, according to health officials.

The United States has told Israel that it must take steps to improve the humanitarian situation in northern Gaza in 30 days or face potential restrictions on military aid.

The UN has long complained of obstacles to getting aid into Gaza and distributing it throughout the war zone, blaming impediments on Israel and lawlessness. The UN said no food aid had entered northern Gaza between October 2 and October 15.

On Wednesday, the Israeli military unit that oversees aid and commercial shipments said 50 trucks had entered northern Gaza.

Ismail al-Thawabta, the Director-general of the Government Media Office in the Gaza strip, said Israeli comments about allowing aid into the enclave were misleading.

He said the Israeli military has maintained a comprehensive siege on the far north of Gaza for 170 consecutive days, closing all humanitarian access points. He said 342 people had been killed in the Israeli assault over the last 10 days.