Eyewitnesses reported the Boeing 777 aircraft approaching the runway at an unusual nose-high, low-tail attitude. The debris field indicated touchdown occurred much earlier on the runway than is typical.
Aviation experts speculate that the tail hit first, disabling flight controls and sending the 777 sliding and spinning up the runway as parts of the aircraft (the tail and parts of the wingtips) flew off.
Officials told MSNBC there is no indication that terrorism was a factor. Weather does not seem to have been a factor either. Winds were clocked at 5-10 miles per hour, temperatures were in the mid-60s and skies were partly cloudy.
The pilots made no distress calls, and no emergency vehicles approached the runway until after the crash landing occurred.
No passenger list or reports of casualties were available at this writing, but photos taken by passengers showed groups of them exiting the hulk of the aircraft via a slide on the left side and walking away. News reports put the number of passengers onboard at about 300.
"I just crash landed at SFO," read the message accompanying the picture from David Eun. "Tail ripped off. Most everyone seems fine. I'm ok. Surreal..."
Photos of the crash site show a large portion of the top of the aircraft burned out, which apparently happened after at least some of the passengers were able to escape. The fire likely was caused by remaining fuel in the aircraft.
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.
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 One World 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.
For now, San Francisco Airport remains closed.
This report includes material from the Associated Press.