Ethiopia Plane Crash
Ethiopia Plane Crash

Tributes and condolences are pouring in for the 157 people who lost their lives when an Ethiopian Airlines jet crashed Sunday near Addis Ababa.

The victims were from at least 35 countries and included 22 United Nations staff members heading to a U.N. environmental conference in Nairobi.

Flags at the conference were lowered to half-staff Monday. The Nairobi conference and a General Assembly meeting in New York both opened with moments of silence.

Iimaltoonni Digdamni Kora Sagantaa Qilleensa Naann
The United Nations flag flies at half-staff in memory of the victims of the Ethiopian Airlines plane crash, in Geneva, Switzerland, March 11, 2019.

"A global tragedy has hit close to home, and the United Nations is united in grief. I extend my deepest condolences to the families and loved ones of all the victims, to the government and people of Ethiopia, and all these affected by this disaster," Secretary-General Antonio Guterres said in New York.

Delegates at the United Nations Environment Programme (UNEP) world environmental forum observe a minute's silence in memory of the victims of Ethiopian Airlines Flight ET 302 plane crash, at the UN complex within Gigiri in Nairobi, Kenya, March 11, 2...
UN in Nairobi Pays Respect to Ethiopian Crash Victims
Delegates at the United Nations Environment Assembly, meeting in Kenya, held a moment of silence Monday for the victims of Sunday's Ethiopian Airlines crash.At least 5,000 delegates, including environment ministers, experts, and activists gathered Monday at the United Nations offices in Nairobi.They paid respects to the 157 people who died in Sunday’s Ethiopian Airlines crash.The victims came from more than 30 nations and included 22 U.N. staff members.

The victims were also remembered at U.N. refugee headquarters in Geneva and at the State Department in Washington.

"This particular flight was used regularly by humanitarian and development organizations in the region, people working each and every day to save lives and make the world just a little bit better place despite the risks," the head of the U.S. Agency for International Development, Mark Green, said Monday.

Menur Nur Mohamed lost his brother Ahmed on the doomed plane. Ahmed Nur Mohamed was the co-pilot.

"Me and my brother grew up together. He wasn't only my brother, but also my friend," Mohamed told Tsion Tadesse of VOA's Horn of Africa service.

A member of the Ethiopian Airline Pilots' Associat
FILE - A member of the Ethiopian Airline Pilots' Association mourns as she attends a memorial service for victims of the Ethiopian Airlines plane that crashed, in Addis Ababa, Ethiopia, March 11, 2019.

Mohamed said he learned of his brother's death when the head of Ethiopian Airlines mentioned his name.

"[My brother] called me Saturday night to tell me has a flight Sunday morning and will call me when he gets back. But I didn't know where he was flying. When I heard about the accident Sunday morning, I called his friends to find out where he flew. I was trying to calm down our parents when the CEO of Ethiopian Airlines gave the press conference," Mohamed said.

?Investigators have found the flight data recorder and the cockpit voice recorder, which they hope will give them clues as to why the Boeing 737 Max 8 jet went down en route to Nairobi.

At least two witnesses say they saw smoke coming from the back of the plane before it crashed.

WATCH: US Experts to Help With Ethiopian Plane Crash Probe

Max 8 jets grounded

The Max 8 was the same model as the one that crashed into the Java Sea in October, just minutes after taking off from Jakarta, killing 189.

Indonesian investigators said information from the flight data recorder showed the plane's automatic safety system repeatedly pushed it downward despite the pilots' desperate attempts to maintain control.

But Ethiopian Airlines chief Tewolde GebreMariam said Sunday he could not rule out anything as the cause of Sunday's crash.

"Ethiopian Airlines is one of the safest airlines in the world," he told reporters at the crash site.

He stood inside the crater where the airliner went down. The ground was littered with jet parts and body bags.

The airline, along with carriers in China, Indonesia and the Cayman Islands, have grounded their Max 8 jets.

Boeing shares plunged 7 percent Monday on Wall Street.

WATCH: International experts investigate crash

Tsion Tadesse, Peter Clottey and Margaret Besheer contributed to this report.