US plane maker Boeing is facing questions after an Ethiopian Airlines 737 crash on Sunday killed all 157 people on board.
It was the second crash in five months involving a 737 Max 8, and comparisons are being drawn with a Lion Air accident in Indonesia last October.
China's aviation regulator has ordered local airlines to ground any planes of the same model.
However, experts warn it is too early to say what caused the latest disaster.
Ethiopian Airlines shared this image of CEO Tewolde Gebremariam at the crash site in Kenya
Ethiopian Airlines says the plane, flight ET302, crashed at 08:44 local time (05:44 GMT), just six minutes after it left Addis Ababa.
The aircraft, bound for Nairobi, came down near the town of Bishoftu, 60km (37 miles) south-east of the capital.
The pilot had reported difficulties and had asked to return to Addis Ababa, the airline said.
"At this stage, we cannot rule out anything," Ethiopian Airlines CEO Tewolde Gebremariam told reporters at Bole International Airport in the capital.
Passengers from more than 30 countries were on board the flight, including 32 Kenyans, 18 Canadians, and seven Britons.
At least 19 victims were affiliated with the United Nations, according a UN official.
Slovak MP Anton Hrnko also confirmed via Facebook that his wife and two children were on the plane.
In response to the accident, Ethiopia has declared Monday a national day of mourning.