Rescue vehicles were on the scene immediately afterwards.
The airport has been closed -- no flights were being allowed in or out of SFO at this time.
Television footage showed debris strewn about the tarmac and pieces of the plane lying on the runway.
Fire trucks had sprayed a white fire retardant on the wreckage.
BELOW: Video of the scene posted on YouTube by straylor/360 Kid.
Asiana 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 oneWorld alliance, anchored by American Airlines and British Airways.
The 777-200 is a long-range plane from Boeing. The twin-engine aircraft is one of the world's most popular long-distance planes, often used for flights of 12 hours or more, from one continent to another. The airline's website says its 777s can carry between 246 to 300 passengers.
The last time a large U.S. airline lost a plane in a fatal crash was an American Airlines Airbus A300 taking off from JFK in 2001.
Smaller airlines have had crashes since then. The last fatal U.S. crash was a Continental Express flight operated by Colgan Air, which crashed into a house near Buffalo, N.Y. on Feb. 12, 2009. The crash killed all 49 people on board and one man in a house.