Search and rescue teams are looking for a Malaysia Airlines passenger jet with 239 people aboard.
The airline says it lost contact with a plane. It took off from Kuala Lumpur to Beijing.
According to China's state news agency, the plane lost communication over Vietnam with a control department in Ho Chi Minh City at 1:20 a.m. Xinhua reported the radar signal for the Boeing 777-200 also was lost.
Malaysia Airlines says the plane was carrying 227 passengers, including two infants, and 12 crew members. 4 Americans, including one of the babies were on board.
The airline says it's working with authorities who activated their search and rescue teams to locate the aircraft. The route would take it from Malaysia across to Vietnam and China.
"Our focus now is to work with emergency responders and mobilize its full support," said an airline official. "Our thoughts and prayers are with all the affected passengers and crew and their families."
At Beijing's airport, worried relatives and friends of passengers have been asked to gather to a hotel about a 30 minute drive from the airport to wait for further information. Airport authorities have provided shuttle bus service.
The 777 had not had a fatal crash in its 20 year history until the Asiana crash in San Francisco in July 2013.