The World Central Kitchen logo could be seen on items inside the charred interior of the northernmost and southernmost cars. The car in the middle was left with a gaping hole in its roof, which was clearly marked with the group’s logo. All three vehicles, though far apart from each other, were on or near the Al-Rashid coastal road.

It remained unclear on Tuesday morning what sort of munition struck the cars and whether those explosives were launched from the ground, from a warplane or from a drone.

Six foreign citizens and a Palestinian were killed.

World Central Kitchen said one of those killed was a dual citizen of the United States and Canada, while the others were from Australia, Britain, Gaza and Poland. It did not give their names.

Prime Minister Anthony Albanese of Australia identified one of the victims as Zomi Frankcom, an Australian citizen and a senior manager at World Central Kitchen. “The tributes flowing for Lalzawmi ‘Zomi’ Frankcom tell the story of a life dedicated to the service of others, including her fellow Australians during natural disasters,” Penny Wong, the foreign minister, said on social media.

Damian Sobol, an aid worker from the southeastern Polish city of Przemysl, died in the attack, according to the city’s mayor, Wojciech Bakun. “There are no words to describe what people who knew this fantastic boy feel at this moment,” he said in a post on social media.

Palestinian medics retrieved the bodies of the seven victims and took them to a hospital in Deir al-Balah, according to the Palestine Red Crescent Society. The bodies of the foreigners were to be taken out of Gaza into Egypt, the group said.

A Palestinian working as a driver and translator for World Central Kitchen died in the attack. Agence France-Presse and Reuters, which gave different names for him, released photos of his body being carried at his funeral in Rafah, in southern Gaza.

David Cameron, the British foreign minister, said on social media that “it is essential that humanitarian workers are protected and able to carry out their work.” He called on Israel “to immediately investigate and provide a full, transparent explanation of what happened.”

At least 196 aid workers were killed in Gaza and the West Bank between October 2023 and late March, according to Jamie McGoldrick, a senior U.N. relief official. “This is not an isolated incident,” he said, later adding: “There is no safe place left in Gaza.”

The prime minister appeared to take responsibility for the ‘unintentional’ attack.

In a video statement on Tuesday, Prime Minister Benjamin Netanyahu of Israel referred to a “tragic case of our forces unintentionally harming innocent people in the Gaza Strip.” Mr. Netanyahu did not specifically name World Central Kitchen in his remarks.

But an Israeli official familiar with the matter, who spoke on condition of anonymity because the strike was still under investigation, clarified that the prime minister was referencing the strike.

“It happens in war, we are fully examining this, we are in contact with the governments, and we will do everything so that this thing does not happen again,” Mr. Netanyahu said.

An Israeli military official, who spoke on condition of anonymity to discuss an internal investigation, said the military had concluded it was responsible for the strike on the convoy. Gen. Herzi Halevi, the Israeli military chief of staff, is expected to review findings of an initial inquiry into the incident on Tuesday evening, the official said.

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A spokesman for Israel’s military, Rear Adm. Daniel Hagari, said the investigation had been referred to the Fact Finding and Assessment Mechanism, a military body tasked with investigating accusations and probing the circumstances behind battlefield incidents. “We will be opening a probe to examine this serious incident further,” he said. “This will help us reduce the risk of such an event from occurring again.”

The Israeli military said the mechanism was an “independent, professional, and expert body.” Human rights groups have generally been critical of the Israeli military’s ability to transparently investigate itself, charging that probes are often long and rarely lead to indictments.

The World Central Kitchen aid ship is headed back to Cyprus.

At the time of the strike, workers had unloaded 100 tons of aid from the Jennifer, a World Central Kitchen vessel that had left the Cypriot port of Larnaca last weekend and arrived in Gaza on Monday. Another 240 tons were to be unloaded on Tuesday, according to Theodoros Gotsis, a spokesman for the Cypriot foreign ministry.

Mr. Gotsis said that the Jennifer instead left Gaza to sail back to Larnaca on Tuesday. He added that several more tons of aid was waiting at warehouses in Larnaca, but that it was not clear when and whether such a mission would take place.

Patrick Kingsley, Rawan Sheikh Ahmad, Gabby Sobelman, Matina Stevis-Gridneff, Lauren Leatherby and Nader Ibrahim contributed reporting to this article.