A Boeing 777 aircraft that crash-landed at San Francisco airport killing two people did not have mechanical problems, an airline official has said.

The head of the South Korean airline Asiana, Yoon Young-doo, did not rule out human error but said the pilots were experienced veterans.

Most of the 307 people on board were injured, 49 of them seriously.

The plane came down short of the runway, ripping off its tail, after apparently hitting a sea wall, reports the BBC.

One survivor said the plane came in to land too fast and too low, but there was no warning of problems.

Passengers and crew escaped down emergency slides as it burst into flames.

Yoon apologised "deeply" for the effect the accident had had on all those involved, bowing in front of TV cameras at a Seoul news conference.

He said there was no emergency alarm and the crew had made the usual requests to passengers to fasten their seatbelts to prepare for landing.

"Currently we understand that there were no engine or mechanical problems," he said.

The pilots were veterans, he added, and one had more than 10,000 flying hours.

Asiana confirmed that two female Chinese teenagers died in the crash. They had been seated at the back of the aircraft.

They are believed to be the first-ever fatalities in a Boeing 777 crash.

The twin-engine aircraft has a good safety record for long-haul and is used by many major carriers.

The only previous notable crash occurred when a British Airways plane landed short of the runway at London's Heathrow Airport in 2008.

Source: http://adevision..com/2013/07/us-air-crash-no-mechanical-cause.html