Gaza health authorities said Israeli forces on Thursday shot dead more than 100 Palestinians as they waited for an aid delivery, but Israel blamed the deaths on crowds that surrounded aid trucks, saying victims had been trampled or run over bringing the death toll since the start of the Israel-Hamas war to more than 30,000, Reuters reports.

At least 112 people were killed and more than 280 wounded in the incident near Gaza City, Palestinian health officials said.

The loss of civilian lives was the biggest in weeks. Hamas said the incident could jeopardize talks in Qatar aimed at securing a ceasefire and the release of Israeli hostages it is holding.

The violence was quickly condemned by Arab countries, and U.S. President Joe Biden expressed concern it would add to the difficulty of negotiating a cease-fire in the nearly five-month conflict, according to AP News.

Israel disputed the account provided by officials in Hamas-run Gaza, which has been bombarded by Israeli forces for months since the Palestinian militant group’s deadly rampage in southern Israel on October 7.

The Israeli military said the trucks were operated by private contractors as part of an aid operation that it had been overseeing for the past four nights.

One Israeli official said there had been two incidents, hundreds of metres apart. In the first, dozens were killed or injured as they tried to take aid from the trucks and were trampled or run over.

He said there was a second, subsequent incident as the trucks moved off. Some people in the crowd approached troops who felt under threat and opened fire, killing an unknown number in a “limited response”, he said. He dismissed the casualty toll given by Gaza authorities but gave no figure himself.

In a later briefing, Israel Defense Forces spokesman Rear Admiral Daniel Hagari also said dozens had been trampled to death or injured in a fight to take supplies off the trucks.

He said tanks escorting the trucks had subsequently fired warning shots to disperse the crowd and backed away when events began to get out of hand. “IDF strike was conducted towards the aid convoy,” he said.

“The IDF was there conducting a humanitarian operation to secure the humanitarian corridor and allow the aid convoy to reach its designated distribution point,” Hagari added.

The U.S. State Department said it was urgently seeking information on the incident as did the French foreign ministry.

Hamas issued a statement rejecting the Israeli account.

It said the Health Ministry had presented “undeniable” evidence of “direct firing at citizens, including headshots aimed at immediate killing, in addition to the testimonies of all witnesses who confirmed being targeted with direct fire without posing any threat to the occupying army.”

The White House said Biden discussed the “tragic and alarming incident” with the leaders of Egypt and Qatar, as well as ways to secure the release of Israeli hostages and a six-week ceasefire.

Palestinian President Mahmoud Abbas said it was an “ugly massacre” by Israel, and French foreign ministry spokesperson Christophe Lemoine said Israel was responsible under international law for protecting aid distribution to civilians.

The Pentagon expressed alarm but declined to assign any blame. “These are human beings that are trying to feed themselves” Air Force Major General Patrick Ryder, a Pentagon spokesperson, told a news briefing. “We’re all kind of looking at that and saying: ‘What happened here’?.”

The Palestinian health authorities said 30,035 Palestinians were now confirmed killed and more than 70,000 wounded in Israel’s offensive, launched after the October 7 attack in which Israel said Hamas gunmen killed 1,200 people and abducted 253.

Much of Gaza has been reduced to rubble and most of its 2.3 million population have been displaced from their homes at least once.

Aid deliveries to northern Gaza have been sparse and chaotic, passing through more active military zones to an area where the U.N. says many are starving, with videos showing desperate crowds surging around supply trucks.

U.N. and other relief agencies have complained that Israel has blocked or restricted their attempts to get aid in. Israel denies putting any restrictions on humanitarian aid, according to Reuters.

Philippe Lazzarini, head of the U.N. Palestinian aid agency UNRWA, told reporters in Jerusalem that the supply of aid into Gaza as a whole had halved since January.