U.S. investigators are examining on Sunday the hard landing of an Asiana airlines jet that killed two people and injured hundreds at the San Francisco international airport.

The Boeing 777, with 291 passengers and 16 crewmembers on board, originally took off from Shanghai, China, but made a stop in Seoul, South Korea, en route to the United States.

The plane apparently hit a barrier Saturday at the head of Runway 28 at the airport, which is located some 20 kilometers (about 12.5 miles) south of San Francisco.

National Transportation Safety Board, or NTSB, investigators arrived at the airport on Saturday evening and suspended the airport's normal activities for three hours, affecting hundreds of flights and airports all around the nation.

The incident does not appear to be the result of a criminal act or terrorism, FBI special agent David Johnson said.

Videos taken by witnesses show that the tail section of the aircraft broke off and the plane made a belly landing - without deploying its landing gear - on the runway and slid into a pasture where it was enveloped in a dense cloud of white smoke.

Many passengers exited the burning aircraft by sliding down the escape ramps that were deployed after the plane came to a halt.

The two fatalities carried Chinese passports, the South Korean vice consul general in San Francisco, Hong Sung Wok, said. EFE