A Malaysian government official says investigators have concluded that one of the pilots or someone else with flying experience hijacked the missing Malaysia Airlines jet.
The official, who is involved in the investigation, says no motive has been established, and it is not yet clear where the plane was taken. The official spoke on condition of anonymity because he was not authorized to brief the media.
The official said that hijacking was no longer a theory. "It is conclusive."
The jet disappeared last Friday on a flight from Kuala Lumpur, Malaysia to Beijing, China. There were 239 passengers and crew on board.
Two communications systems on board the Boeing 777 failed, one after the other, as the plane was flying at 35,000 feet.
Satellites picked up signals from the plane for four hours after it disappeared. Those signals suggest the plane was flying west toward the Indian Ocean, away from its destination, although it's possible the plane could have been on the ground for some of that time.
Despite a widespread search, there's still no sign of the missing plane.