A Boeing 777 lies burned beside the runway after it crash-landed at San Francisco International Airport on Saturday. Ezra Shaw / Agence France-Presse

DEAD & SURVIVORS | Two Chinese teenagers die in crash. More than 180 others injured, 49 seriously.

CAUSE | Witness says plane was coming in too low and clipped sea wall, causing the tail to fall off. Asiana officials say 'there were no problems caused by the 777-200 plane or (its) engines'.

Passenger Xu Da was sitting at the rear of the Asiana Airlines Boeing 777 as it was coming in to land at San Francisco International Airport on Saturday.

"I was very scared when I felt the violent bangs and the sounds of the crash," he said.

The plane crash-landed and burst into flames with more than 300 passengers and crew onboard, including 141 Chinese, 77 South Koreans and 61 US citizens.

Two Chinese teenagers died and more than 180 passengers were injured, 49 seriously.

An investigation into the cause of the accident has begun.

"The plane flew extremely low, even as low as the sea wall, as I was looking out of the window. I felt the plane drop suddenly, but then I felt a surge of power from the back and the plane tried to ascend again," Xu said.

"I mumbled a prayer for a safe landing and held the seat tightly in front of me. All of a sudden, I heard an almighty noise from the back of the plane. Oxygen masks dropped from the overhead compartments and I smelled burning and saw flames."

He recalled that as soon as the plane came to a halt, the scene inside the cabin was one of chaos. People rushed to stand up and retrieve their luggage instead of fleeing the stricken aircraft.

"I thought something unusual had happened, but did not imagine it was so serious," he said. "However, my wife was very calm and even managed to collect some trivial stuff that fell from an overhead compartment. I urged her to hurry up, and when I turned back to put my bag over my shoulder, I saw the light coming in from outside."

Xu only realized how serious the situation was when he discovered that most of the plane's kitchen area had disappeared, leaving a huge hole.

"Without thinking, I held onto my wife and pushed my child out of the plane," he said, stressing that the passengers were calm and orderly as they followed the instructions of the cabin crew.