World Central Kitchen founder José Andrés said Monday that several of the group’s employees were killed in an Israeli airstrike in Gaza. Andrés, a celebrity chef, called those who died his “sisters and brothers” and “angels” in a statement on social media.

“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,” Andrés wrote on social media.

“I served alongside [them] in Ukraine, Gaza, Turkey, Morocco, Bahamas, Indonesia,” Andrés wrote of those killed on Monday. “They are not faceless…they are not nameless.”

“If they are aid workers, they are civilians, and civilians are protected from attack under the law of war,” said Brian Finucane, a former legal adviser at the State Department and now a senior adviser at Crisis Group.