At least two people have died and dozens of others are injured after an Asiana Airlines Boeing 777 passenger jet crashed while landing at San Francisco International Airport.

Officials are now saying that one person is unaccounted for, correcting an earlier figure in which they had estimated that upwards of 60 people could be missing.

Airport spokesman Doug Yakel said the flight contained 291 passengers and 16 crew members. He said 181 people were taken to area hospitals after the crash, which occurred just before noon.

San Francisco General Hospital spokeswoman Rachael Kagan said 34 patients had been admitted to the hospital — 11 children and 23 adults.

Kagan added that five people are now listed in critical condition, down from the original 10.

"Five of those remain critically injured; the other five have been upgraded to serious," she said.

The adult patients range in age from their 20 to their 40s. It was not known how old the injured child passengers were.

Plane looked like it 'cartwheeled'

Firefighters and rescue crews were on the scene, spraying the burning jet with white foam. Aerial images broadcast by local news station KTVU showed the blackened wreckage on the tarmac, apparently with its tail broken off and top fuselage ripped open.

Asiana Airlines Flight 214 was travelling from Seoul, South Korea, when it apparently landed and then crashed, FAA spokeswoman Laura Brown said. The flight had originated in Shanghai.

In a video clip posted to YouTube and purportedly showing the crashed plane, smoke can be seen billowing from a silver-coloured jet on the tarmac. Passengers could be seen jumping down inflatable emergency slides.

Krista Seiden witnessed the disaster from a window while waiting to board her own flight at the airport. She told CBC News she was about 400 or 500 yards away from the wreckage.

"It was really scary. I immediately was very concerned for everybody on board the plane; I was trying to get a good line of sight," Seiden said.

"It didn't look like it had a tail; it looked like the tail had come off," she added.

Terrorism ruled out as cause

Asiana Airlines Founded: 1988.

Fleet: 79 planes, including 12 777-200ERs.

Headquarters: Seoul.

Daily flights: 268.

Destinations: 23 countries, 71 cities, plus 12 cities in Korea.

Employees: 9,073 employees, including 3,321 office workers, 4,582 cabin crew and 1,170 technical and ground staff.

Another witness, Stephanie Turner, told ABC News it appeared as if the plane "cartwheeled" after it touched down.

Shaken passengers aboard the aircraft said the flight had been coming in too low for a landing.

The National Transportation Safety Board said it was sending a team of investigators to San Francisco to probe the crash. NTSB spokeswoman Kelly Nantel said Saturday that NTSB Chairman Deborah Hersman would head the team.

FBI special agent Dave Johnson told reporters at a press conference that authorities have found no evidence of terrorism or any criminal act.

Asiana Airlines is a South Korean airline, second in size to national carrier Korean Air. It has recently tried to expand its presence in the United States, and joined the Star Alliance, which is anchored in the U.S. by United Airlines.