7 aid workers killed in Gaza during IDF attack that Israeli official calls 'grave mistake'

'It happens in war," Israeli Prime Minister Benjamin Netanyahu said.

"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," CEO Erin Gore said in a statement. "This is unforgivable."

WCK identified all seven victims on Tuesday. The youngest was Palestinian Saifeddin Issam Ayad Abutaha, 25.

There were three victims from the U.K.: John Chapman, 57; James "Jim" Henderson, 33; and James Kirby, 47.

The victims also included Damian Sobol, 35, of Poland; Jacob Flickinger, 33, of the U.S. and Canada; and Lalzawmi "Zomi" Frankcom, 43, of Australia.

White House press secretary Karine Jean-Pierre said President Joe Biden spoke with WCK founder Jose Andres and "conveyed he is grieving with the entire World Central Kitchen family."

"The president felt it was important to recognize the tremendous contribution World Central Kitchen has made to the people of Gaza and people around the world," Jean-Pierre said. "The president conveyed he will make clear to Israel humanitarian aid workers must be protected."

White House National Security Council spokesman John Kirby offered the administration's strongest reaction to the deadly strike.

"We were outraged to learn of an IDF strike that killed a number of civilian humanitarian workers yesterday from the World Central Kitchen, which has been relentless and working to get food to those who are hungry in Gaza, and quite frankly, around the world," Kirby said. "We send our deepest condolences to their families and loved ones."

Kirby added, "This incident is emblematic of a larger problem and evidence of why distribution of aid in Gaza has been so challenging. But what -- beyond the strike -- what is clear is that the IDF must do much more, much more to improve deconfliction processes so that civilians and humanitarian aid workers are protected."

Israeli Prime Minister Benjamin Netanyahu made his first comments about the deadly incident as he was leaving a hospital after undergoing successful hernia surgery.

"Unfortunately, in the last day, there was a tragic case of our forces unintentionally hitting innocent people in the Gaza Strip," Netanyahu said. "It happens in war, we check it to the end. We are in contact with the governments, and we will do everything so that this thing does not happen again."

Netanyahu later released a second statement, saying, "Israel deeply regrets the tragic incident which claimed the lives of seven humanitarian aid workers."

"Our hearts go out to their families and to their home countries," Netanyahu said. "The IDF is conducting a swift and transparent investigation and we will make our findings public. Israel is fully committed to enabling humanitarian aid to reach the civilian population in Gaza and we will do everything in our power to ensure that such tragedies do not occur in the future."

Israeli President Isaac Herzog also called Andres on Tuesday to express his condolences. In a statement, Herzog said he conveyed to Andres "Israel's commitment to ensuring a through investigation of the tragedy."

Israel’s military chief Herzi Halevi said the airstrike that killed seven foreign aid workers was a "grave mistake," in a statement released via video late Tuesday local time, and translated by Reuters.

Halevi said the strike was "not carried out with the intention of harming WCK aid workers."

"I want to be very clear, the strike was not carried out with the intention of harming WCK aid workers. It was a mistake that followed a misidentification at night, during a war, in very complex conditions. It shouldn't have happened,” Halevi said.

"This incident was a grave mistake. Israel is at a war with Hamas, not with the people of Gaza. We are sorry for the unintentional harm to the members of WCK," he added.

Australian Prime Minister Anthony Albanese demanded accountability for Frankcom's death while describing her as having "the sort of values that are shown by someone going into a very dangerous place in order to assist mankind, your fellow humans, people who she didn't know."

"She just wanted to help out through this charity," Albanese said. "It says everything about the character of this young woman, and so this tragedy and my sincere condolences and that of the Australian government go to Zomi's family, to her friends and all who knew her."

WCK, a non-governmental organization, has been operating in Gaza for months and has said it's served more than 33 million meals since the start of the conflict. It operates over 60 community kitchens in Gaza with the help of about 400 Palestinians on the ground.

U.S. officials are "heartbroken and deeply troubled" by the strike, Adrienne Watson, spokesperson for the White House National Security Council, said in a statement on social media.

"Humanitarian aid workers must be protected as they deliver aid that is desperately needed, and we urge Israel to swiftly investigate what happened," Watson said.

A representative from the organization said WCK was still gathering details about the incident that took place Monday night.

According to the WCK statement, the aid workers were traveling in a three-vehicle caravan, including two armored cars, all branded with the WCK logo. Despite coordinating its movements with the IDF, the team was hit as it was leaving Deir al-Balah warehouse in central Gaza, where it had helped unload more than 100 tons of humanitarian aid brought to Gaza on the maritime route, according to the WCK statement.

"This is a tragedy. Humanitarian aid workers and civilians should NEVER be a target. EVER," the representative said in a statement.

The IDF said in a statement that it was conducting a "thorough review at the highest levels to understand the circumstances of this tragic incident."

"The IDF makes extensive efforts to enable the safe delivery of humanitarian aid, and has been working closely with WCK in their vital efforts to provide food and humanitarian aid to the people of Gaza," the statement said.

Also on Tuesday, Israeli Defense Minister Yoav Gallant referred to the tragic nature of the incident and emphasized the importance of conducting a thorough, professional investigation, which will be followed by the implementation of lessons learned. Gallant highlighted the important work undertaken by international aid organizations, as well as Israel’s commitment to working closely with partner countries and organizations and facilitating the distribution of humanitarian aid.

U.S. Secretary of State Antony Blinken said Tuesday in Paris that the U.S. has spoken to the Israeli government about the missile strike on the WCK team.

"We've spoken directly to the Israeli government about this particular incident we've urged the swift, thorough and impartial investigation to understand exactly what happened," Blinken said.

Blinken said the seven victims "join a record number of humanitarian workers who have been killed in this particular conflict." At least 196 aid workers, including 175 members of the U.N. staff, have now been killed in the Hamas-Israel conflict, according to U.N. Secretary General Antonio Guterres.

"I can only say that for so many of us, we extend our condolences to the loved ones, to the families, friends, colleagues of those who lost their lives, or who were injured," Blinken said. "They have been doing extraordinary, brave work day-in and day-out, and critical work ... starting with the most basic thing of all: food. These people are heroes. They run into the fire. They show the best of what humanity has to offer. They have to be protected."

Officials in the United Kingdom were "urgently working" to verify whether British citizens had been killed, David Cameron, the U.K.'s foreign secretary, said in a statement.

"We have called on Israel to immediately investigate and provide a full, transparent explanation of what happened," he said.

Andres, the founder of WCK, said he was "heartbroken" and "grieving" for the families and friends of the workers who were killed.

"Today @WCKitchen lost several of our sisters and brothers in an IDF air strike in Gaza," he wrote on X.

He added, "I am heartbroken and grieving for their families and friends and our whole WCK family. These are people … angels … I served alongside in Ukraine, Gaza, Turkey, Morocco, Bahamas, Indonesia. They are not faceless … they are not nameless. 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. No more innocent lives lost. Peace starts with our shared humanity. It needs to start now."

IDF spokesperson Daniel Hagari said in a taped message that he had spoken with Andres and "expressed the deepest condolences."

"We will be opening a probe to examine this serious incident further. This will help us reduce the risk of such an event from occurring again," he said, adding, "We will get to the bottom of this and we will share our findings transparently."

ABC News' Joe Simonetti and Bill Hutchinson contributed to this story.