Malaysia Airlines says it has lost contact with a flight from Kuala Lumpur to Beijing carrying 239 passengers and crew.
The airline says on its Facebook page that it deeply regrets losing all contact with Flight MH370 about two hours after it took off from the Malaysian capital early Saturday morning local time.
The airline says it is working with the search and rescue team to locate the aircraft and is calling the families of the passengers and crew.
China's official Xinhua news agency says contact with the plane was lost in Vietnamese airspace. It says the plane never entered China's air traffic control area.
The plane is a Boeing B777-200.
The most recent accident involving a Boeing 777 was the Asiana Airlines crash at the San Francisco International Airport in July, in which three people died.