WATCH LIVE: National Cathedral hosts memorial for World Central Kitchen aid workers killed in Gaza

WASHINGTON (AP) — Mourners gathered Thursday at the National Cathedral in Washington to honor the seven World Central Kitchen aid workers killed by Israeli airstrikes in Gaza this month.

Watch the event in the player above.

José Andrés, the celebrity chef and philanthropist behind the Washington-based World Central Kitchen disaster relief group, is expected to speak at the celebration of life service and cellist Yo-Yo Ma will perform, organizers said.

Douglas Emhoff, husband of Vice President Kamala Harris, and Kurt Campbell, the deputy secretary of state, were among those at the event. Diplomats from more than 30 countries were attending as were officials from both the State Department and the U.S. Agency for International Development.

Democratic Sen. Chris Van Hollen of Maryland, one of the most active lawmakers pushing President Joe Biden to condition military aid on improved Israeli treatment of aid workers and Palestinian civilians, joined the mourners as a lone bagpiper played.

WATCH: José Andrés accuses Israel of deliberately targeting World Central Kitchen members

The aid workers were killed April 1 when strikes from Israeli armed drones ripped through vehicles in their convoy as they left one of World Central Kitchen’s warehouses on a food delivery mission. Those who died were Palestinian Saifeddin Issam Ayad Abutaha; Britons John Chapman, James Kirby and James Henderson; dual U.S.-Canadian citizen Jacob Flickinger; Australian Lalzawmi Frankcom; and Polish citizen Damiam Sobol.

After an unusually swift investigation, Israel said the military officials involved in the attack had violated policy by acting based on a single grainy photo that one officer had contended — incorrectly — showed one of the seven workers was armed. The Israeli military dismissed two officers and reprimanded three others.

The aid workers, whose trip had been coordinated with Israeli officials, are among more than 220 humanitarian workers killed in the Israel-Hamas war that began Oct. 7, according to the United Nations. That includes at least 30 killed in the line of duty.

The international prominence and popularity of Andres and his nonprofit work galvanized widespread outrage over the killings of the group’s workers. The deaths intensified demands from the administration and others that Israel’s military change how it operates in Hamas-controlled Gaza to spare aid workers and Palestinian civilians at large, who are facing a humanitarian crisis and desperately need aid from relief organizations as the U.N. warns of looming famine.

World Central Kitchen, along with several other humanitarian aid agencies, suspended work in the territory after the attack. “We haven’t given up,” World Central Kitchen spokesperson Linda Roth said last week. “We are in funeral mode right now.”

Religious leaders of a range of faiths are set to participate in Thursday’s services. Funerals were held earlier in the workers’ home countries.

Associated Press writer Menelaos Hadjicostis in Nicosia, Cyprus, contributed to this report.