GAZA CITY, Palestinian Territories, June 4, 2025 (AFP) - Twenty-seven people were killed in southern Gaza on Tuesday as Israeli troops opened fire near a US-backed aid centre, with the military saying the incident was under investigation.

United Nations chief Antonio Guterres decried the deaths of Palestinians seeking food aid as "unacceptable" and the UN rights chief condemned attacks on civilians as "a war crime", after a similar shooting near the same site on Sunday.

Gaza's civil defence agency said that "27 people were killed and more than 90 injured in the massacre targeting civilians who were waiting for American aid in the Al-Alam area of Rafah", in the territory's south.

Civil defence spokesman Mahmud Bassal earlier told AFP the deaths occurred "when Israeli forces opened fire with tanks and drones", while Israel said troops fired towards "suspects" who had ignored warning shots.

The International Committee of the Red Cross gave the same death toll but without mentioning the Israeli forces.

The organisation said Gazans face an "unprecedented scale and frequency of recent mass casualty incidents".

The latest shooting occurred about a kilometre (just over half a mile) from a centre run by the US-backed Gaza Humanitarian Foundation (GHF), which Israel has worked with to implement a new aid distribution mechanism.

The United Nations and major aid groups have refused to cooperate with the group over concerns it was designed to cater to Israeli military objectives.

At a hospital in southern Gaza, the family of Reem al-Akhras, who was killed in the shooting at Rafah's the Al-Alam roundabout, were beside themselves with grief.

"She went to bring us some food, and this is what happened to her," her son Zain Zidan said.

Akhras's husband, Mohamed Zidan, said "every day, unarmed people" were being killed.

"This is not humanitarian aid; it's a trap."

The Israeli military maintains that its forces do not prevent Gazans from collecting aid.

Army spokesman Effie Defrin said the Israeli soldiers had fired at suspects who "were approaching in a way that endangered" the troops, adding the "incident is being investigated".

- 'Unconscionable' -

Rania al-Astal, 30, said she had gone to Al-Alam with her husband to try to get food.

"The shooting began intermittently around 5:00 am. Every time people approached Al-Alam roundabout, they were fired upon," she told AFP.

"But people didn't care and rushed forward all at once -- that's when the army began firing heavily."

Fellow witness Mohammed al-Shaer, 44, said at first "the Israeli army fired shots into the air, then began shooting directly at the people".

GHF said the operations at its site went ahead safely on Tuesday.

A military statement said troops saw some people "deviating from the designated access routes" to the Al-Alam aid point, and fired warning shots.

When "the suspects failed to retreat, additional shots were directed near a few individual suspects", it added.

The previous shooting on Sunday killed at least 31 people at the Al-Alam roundabout, rescuers said. A military source acknowledged "warning shots were fired towards several suspects".

Guterres urged an independent investigation into that shooting, with his spokesman on Tuesday saying it was "unacceptable civilians are risking and in several instances losing their lives just trying to get food".

The world body's human rights chief Volker Turk called such attacks "unconscionable".

"Attacks directed against civilians constitute a grave breach of international law and a war crime," he said.

The White House said it was "looking into the veracity" of the reports from Rafah.

- Soldiers killed -

Israel has come under mounting pressure to improve the humanitarian situation in Gaza, where people are facing severe shortages after Israel imposed a more than two-month blockade.

The blockade was recently eased, but the aid community has urged Israel to allow in more food, faster.

GHF's first month of operations, in which it said it had distributed more than seven million meals' worth of food, has been marred by criticism.

The US-backed group named a new chairman on Tuesday, while a consulting firm that helped create it said it had terminated its contract with GHF.

Israel has stepped up its offensive in what it says is a renewed push to defeat Hamas, whose October 2023 attack sparked the war.

Apart from the aid centre incident, Gaza's civil defence agency reported 19 killed in Israeli attacks on Tuesday.

The army said three of its soldiers had been killed in northern Gaza, bringing the number of Israeli troops killed in the territory since the start of the war to 424.

The health ministry in Hamas-run Gaza said at least 4,240 people have been killed since Israel resumed its offensive on March 18, taking the war's overall toll to 54,510, mostly civilians.

Hamas's 2023 attack on Israel resulted in the deaths of 1,218 people, also mostly civilians, according to an AFP tally based on official figures.