An Asiana Airlines flight from Seoul crashed on landing at San Francisco's airport Saturday, the Federal Aviation Authority confirmed.
It was not immediately known if there were casualties. Initial images from the scene showed smoke billowing from the plane and emergency exits open from the plane's fuselage.
The plane was a Boeing 777, FAA spokesman Lynn Lunsford said. It crashed on runway 28L at San Francisco International Airport, he said.
There were 291 people aboard, KCBS radio reported.
Laura Brown, spokeswoman for the FAA in Washington, said Asiana Flight 214 from Seoul was attempting to land at San Francisco International Airport when it crashed.
"All we know is that a foreign airline, Asiana Airlines Flight 214 arriving from Seoul, South Korea, crashed while landing,'' she said. "That's all I've got right now.
The National Transportation Safety Board was dispatching a team of crash investigators to the site.
A video clip posted to Youtube showed smoke coming from a silver-colored jet on the tarmac. Passengers could be seen jumping down the inflatable emergency slides. Images showed the the body of the plane largely intact but with severe fire damage.
The tail of the airplane was separated from the aircraft. Weather at the time was clear.
The crash is the first major commercial jet to crash in the United States since a November 2001 crash in New York.
The last fatal accident involving a commercial flight in the United States was Colgan Air Flight 3407, which crashed near Buffalo, killing 50 people, on Feb. 12, 2009.
Tthere has not been an accident involving a major domestic carrier since an American Airlines flight to the Dominican Republic crashed after takeoff in Queens in November 2001, killing all 260 people on board.
The airline is based in Seoul, South Korea. Its website says its Boeing 777 can carry between 246 to 300 passengers.