Ethiopian Airlines crash was 3rd deadliest incident in UN history There were 21 staffers on board when the plane crashed Sunday.

The Ethiopian Airlines crash is raising question about the safety of the model plane that was used, but for many the disaster has a much more personal impact.

Of the 157 people who were killed in Sunday's crash, 21 of those on board were United Nations staffers.

"A global tragedy has hit close to home and the United Nations is united in grief," Secretary General Antonio Guterres said Monday.

"Our colleagues were women and men, junior professionals and seasoned officials, hailing from all corners of the globe and with a wide array of expertise. They all had one thing in common: a spirit to serve the world and to make it a better place for us all," Guterres said.

According to data from the U.N., this crash could be the third deadliest incident involving the intergovernmental organization.

There were 102 U.N. staffers killed in the 2010 earthquake in Haiti, and in 2011 a U.N. peacekeeping plane crashed in the Democratic Republic of Congo where 32 people - which was a mix of U.N. staffers and individuals who worked for non-governmental organizations but were working alongside the U.N. at the time - died.

Two of the other deadliest incidents involving U.N. staffers were the bombing of the U.N. headquarters in Baghdad in 2003, where 15 U.N. personnel were killed along with eight others who worked at non-governmental organizations, and the bombing of the U.N. office in Algiers in 2007 where 17 U.N. staffers were killed.

Among the 21 U.N. staffers killed in Sunday's crash, there were representatives from nine different agencies including the U.N. High Commissioner for Refugees, the Food and Agriculture Organization of the U.N., and the World Food Programme.

"It's a very sad day here and people are mourning their colleagues," U.N. spokesperson Stephane Dujarric told ABC News.

In addition to the U.N. staffers, many others on board the crashed plane worked at various charities and non-governmental organizations who did work with the U.N. Many were on their way to an environmental conference run by the U.N. in Nairobi.

"It's the kind of flight where... you'd board the plane and would know that you'd know four or five people on the plane," Dujarric said.

Though the number of individuals lost from specific U.N. agencies may change, Dujarric said that the group with the most personnel on board was the World Food Programme, who lost seven staffers in the crash.

The WFP has named and identified the seven staffers, noting that they ranged in age from 26 to 59 years old, and six of the seven were based in their Rome office.

"As we confront this terrible loss, we reflect that all these WFP colleagues were willing to travel and work far from their homes and loved ones to help make the world a better place to live in," the WFP executive director David Beasley said in a statement released Sunday.

"That was their calling, as it is for the rest of the WFP family," Beasley said in his statement.