U.S. President Joe Biden said late Tuesday he is “outraged and heartbroken” after an Israeli airstrike in Gaza killed seven workers from the aid group World Central Kitchen.

“They were providing food to hungry civilians in the middle of a war. They were brave and selfless. Their deaths are a tragedy,” Biden said in a statement.

The U.S. leader said Tuesday’s attack was not a stand-alone incident, and that Israel “has not done enough to protect aid workers trying to deliver desperately needed help to civilians.”

“The United States will continue to do all we can to deliver humanitarian assistance to Palestinian civilians in Gaza, through all available means,” Biden said. “I will continue to press Israel to do more to facilitate that aid. And we are pushing hard for an immediate ceasefire as part of a hostage deal.”

World Central Kitchen said it was immediately pausing its humanitarian efforts in the region following the attack.

The charity said in a statement that it had completed a delivery of 100 tons of food aid to a warehouse in Deir al-Balah, and that a convoy of two armored cars with the group’s logo was leaving the site when it was struck.

World Central Kitchen said the group had coordinated its movements in advance with the Israeli military.

Israeli Prime Minister Benjamin Netanyahu acknowledged that the country’s forces had carried out the “unintended strike … on innocent people.”

“Unfortunately, in the past day there was a tragic event in which our forces unintentionally harmed non-combatants in the Gaza Strip,” Netanyahu said in a video statement.

“This happens in war. We are conducting a thorough inquiry and are in contact with the governments. We will do everything to prevent a recurrence.”

Those killed include a Palestinian, citizens of Australia, Poland, Britain and a dual U.S.-Canadian citizen, the aid group said.

The Palestine Red Crescent Society said it recovered the seven bodies Tuesday in a “challenging operation spanning several hours,” and that they were taken to hospitals in preparation for being evacuated through the Rafah crossing in southern Gaza.

World Central Kitchen CEO Erin Gore called the attack “unforgivable.”

“This is not only an attack against WCK, this is an attack on humanitarian organizations showing up in the most dire of situations where food is being used as a weapon of war,” Gore said.

WCK founder José Andrés said on social media he was “heartbroken and grieving” after losing “several of our sisters and brothers in an IDF strike in Gaza.”

“The Israeli government needs to stop this indiscriminate killing,” Andrés said. “It needs to stop restricting humanitarian aid, stop killing civilians and aid workers, and stop using food as a weapon. No more innocent lives lost. Peace starts with our shared humanity. It needs to start now.”

White House press secretary Karine Jean-Pierre said U.S. President Biden called Andres to express his “deepest condolences” and to say “he is grieving with the entire World Central Kitchen family.”

The group had begun using a maritime route to bring badly needed food to Gaza after humanitarian groups complained of shipments on trucks being held up by the Israeli military and a lack of safe access to areas where people need help.

The chief spokesman for the Israel Defense Forces, Rear Adm. Daniel Hagari, said Tuesday he had spoken with Andrés and expressed the military’s “deepest condolences.”

Hagari said Israel at the “highest levels” is examining what happened and how.

“For the last few months, the IDF has been working closely with the World Central Kitchen to assist them in fulfilling their noble mission of helping bring food and humanitarian aid to the people of Gaza,” Hagari said.

“WCK also came to help Israelis after the massacre of October 7. They were one of the first NGOs here,” Hagari said. “The work of WCK is critical. They are the front lines of humanity.”

U.N. humanitarian chief Martin Griffiths said Tuesday he is “outraged” by the attack and called the actions of those responsible “indefensible.”

“All this talk about cease-fires, and still this war steals the best of us,” Griffiths said in a statement.

Australian Prime Minister Anthony Albanese confirmed Tuesday the death of an Australian aid worker, Lalzawmi “Zomi” Frankcom, saying his government expects “full accountability.”

“This is a human tragedy that should never have occurred that is completely unacceptable,” Albanese told reporters.

Albanese said humanitarian workers and all innocent civilians “need to be provided with protection.”

Polish Foreign Minister Radoslaw Sikorski said on social media he asked Israel’s ambassador to Poland for an urgent explanation. Sikorski also expressed condolences to the family of the Polish worker killed and to all civilian victims in the Gaza Strip.

British Foreign Secretary David Cameron said Tuesday his country’s government was working to verify reported deaths of British nationals in the strike.

“These were people who were working to deliver life-saving aid to those who desperately need it,” Cameron said in a statement. “It is essential that humanitarian workers are protected and able to carry out their work.”

European Union foreign policy chief Josep Borrell condemned the attack and called for an investigation.

“Despite all the demands to protect civilians and humanitarian workers, we see new innocent casualties,” Borrell said.

Israel launched its campaign to eliminate Hamas after the Oct. 7 Hamas attack on Israel that killed 1,200 people, according to Israeli tallies, and led to the capture of about 250 hostages.

Israel’s counter-offensive in Gaza has killed more than 32,900 people, two-thirds of them women and children, according to the Hamas-run Gaza health ministry. The Israeli military says one-third of those killed have been militants.

Some information for this report was provided by The Associated Press, Reuters and Agence France-Presse.