Some of Israel's closest allies, including the United States, on Tuesday condemned the deaths of seven aid workers who were killed by airstrikes in Gaza — a loss that prompted multiple charities to suspend food deliveries to Palestinians on the brink of starvation.

The deaths of the World Central Kitchen workers threatened to set back efforts by the US and other countries to open a maritime corridor for aid from Cyprus to help ease the desperate conditions in northern Gaza.

President Joe Biden issued an unusually blunt criticism of Israel by its closest ally, suggesting that the incident demonstrated that Israel was not doing enough to protect civilians.

Aid workers who were killed by airstrikes: James Henderson (left), Lalzawmi Frankcom, John Chapman, James Kirby and Damian Sobol.

"Israel has not done enough to protect aid workers trying to deliver desperately needed help to civilians,” he said, adding he was "outraged and heartbroken" by their killings.

"Incidents like yesterday’s simply should not happen,” he added. "The United States has repeatedly urged Israel to deconflict their military operations against Hamas with humanitarian operations, in order to avoid civilian casualties.”

Ships still laden with some 240 tons of aid from the charitable group turned back from Gaza just a day after arriving, according to Cyprus. Other humanitarian aid organizations also suspended operations in Gaza, saying it was too dangerous to offer help. Israel has allowed only a trickle of food and supplies into Gaza's devastated north, where experts say famine is imminent.

The dead from Monday night's strikes included three British citizens, Polish and Australia nationals, a Canadian-American dual national and a Palestinian. Those countries have been key backers of Israel's nearly 6-month-old offensive in Gaza, and several of them denounced the killings.

Children wait to receive food cooked by a charity kitchen amid shortages of food supplies in Rafah. Reuters

Israel already faces growing isolation as international criticism of the Gaza assault has mounted. On the same day as the deadly airstrikes, Israel stirred more fears by apparently striking Iran’s consulate in Damascus and killing two Iranian generals. The government also moved to shut down a foreign media outlet - Qatari-owned Al Jazeera television.

The hit on the charity’s convoy also highlighted what critics have called Israel’s indiscriminate bombing and lack of regard for civilian casualties in Gaza.

Israel's military chief, Lt. Gen. Herzi Halevi, announced the results of a preliminary investigation early Wednesday.

"It was a mistake that followed a misidentification - at night during a war in very complex conditions. It shouldn’t have happened,” he said. He gave no further details. He said an independent body would conduct a "thorough investigation” that would be completed in the coming days.

Israeli Prime Minister Benjamin Netanyahu had earlier acknowledged the "unintended strike ... on innocent people” and said officials would work to ensure it does not happen again.

Members of "World Central Kitchen" prepare food for Palestinians, in the location given as Gaza. File/Reuters

World Central Kitchen said it had coordinated with the Israeli military over the movement of its cars. Three vehicles moving at large distances apart were hit in succession. They were left incinerated and mangled, indicating multiple targeted strikes.

At least one of the vehicles had the charity’s logo printed across its roof to make it identifiable from the air, and the ordnance punched a large hole through the roof. Footage showed the bodies at a hospital in the central Gaza town of Deir al-Balah, several of them wearing protective gear with the charity’s logo.

More than 32,900 Palestinians have been killed in the war, around two-thirds of them women and children, according to Gaza’s Health Ministry, which does not distinguish between civilians and combatants in its count.

Celebrity chef José Andrés, who founded the World Central Kitchen charity, said he was "heartbroken” by the deaths of the staffers.

"The Israeli government needs to stop this indiscriminate killing. It needs to stop restricting humanitarian aid, stop killing civilians and aid workers, and stop using food as a weapon,” he wrote on X, formerly Twitter.

Palestinians carry the body of a foreign employee from the WCK, who was killed in an Israeli airstrike. Reuters

The US, Britain, Poland, Australia and Canada all called on Israel to give answers on the deaths. Israeli Defense Minister Yoav Gallant launched an investigation and ordered the opening of a joint situation room enabling coordination between the military and aid groups.

But anger among its allies could put new pressure on Israel.

The British government summoned Israel’s ambassador for a rebuke and called for an immediate humanitarian pause to allow more aid in and the release of hostages.

British Prime Minister Rishi Sunak told Netanyahu that he was "appalled” by the workers' deaths and described the situation in Gaza as "increasingly intolerable.”

A senior Canadian government official said there will be a joint formal diplomatic rebuke at the foreign ministry in Israel on Wednesday. The official also said a top official with Canada’s Global Affairs department made a formal representation to Israel ambassador’s to Canada on Tuesday. The official spoke on condition of anonymity as they were not authorized to speak publicly on the matter.

The deaths sent a further chill through U.N. agencies and other aid groups that have said for months that sending truck convoys around Gaza - particularly in the north - has been extremely difficult because of the military’s failure to either grant permission or ensure safe passage. Israel has barred UNRWA, the main U.N. agency in Gaza, from making deliveries to the north.

The US and other countries have been working to set up the sea passage from Cyprus to get around the difficulties.

Associated Press