A Boeing 777 aircraft has crash-landed at San Francisco international airport, killing at least two people and injuring dozens more, officials say.

Pictures posted on Twitter showed passengers jumping down the inflatable emergency slides and leaving the area, as plumes of smoke rise from the plane.

Fire fighters and rescue teams are at the scene of the downed Asiana Airlines Flight 214, which had taken off from South Korea's capital, Seoul.

The cause of the crash is unclear.

Early indications suggest the plane came in too short and hit the seawall at the airport.

Eight adults and two children who suffered critical injuries are being treated at San Francisco General Hospital, hospital spokesperson Rachael Kagan said.

There were 291 passengers and 16 crew on board, Asiana said.

Nationalities on board included 141 Chinese, 77 South Koreans and 61 US citizens, the airline said.

Rescue teams initially took 49 people deemed to be in a serious condition to nearby hospitals, officials said.

Some 190 people walked to safety from the plane, many of whom were later treated for minor injuries.

Most of the remaining passengers were waiting in the airport terminals uninjured. One person remained unaccounted for.

While the sequence of events remains unclear, it appeared the plane landed and then crashed on San Francisco International Airport's Runway 28L, said Federal Aviation Administration spokeswoman Laura Brown.

Footage of the scene showed debris strewn on the runway and smoke pouring from the jet, as fire crews sprayed a white fire retardant into gaping holes in the craft's roof.

One engine and the tail fin appeared to have broken away from the main wreckage.
'Out of control'

Passenger David Eun tweeted a picture of people jumping out of the plane's emergency inflatable slides and wrote: "I just crash landed at SFO. Tail ripped off. Most everyone seems fine. I'm ok. Surreal..."

City Mayor Ed Lee: "This is still a fluid and active scene"

Mr Eun, who describes himself as a "digital media guy" and "frequent flier", added: "Fire and rescue people all over the place. They're evacuating the injured. Haven't felt this way since 9/11."

A witness to the crash, Ki Siadatan, said the plane "looked out of control" as it descended over San Francisco Bay to land just before 11:30 (18:30 GMT).

"We heard a 'boom' and saw the plane disappear into a cloud of dust and smoke," he told the BBC. "There was then a second explosion."

He saw events unfold from the balcony of his home in the Millbrae area of San Francisco, which overlooks the airport.

Weather conditions were fine and there was little wind, he added.

Arrivals and departures at the airport have been suspended since the incident.

The twin-engine Boeing 777 has a good safety record as a long-haul aircraft and is used by many major carriers.

Asiana is South Korea's second-largest airline.

【新聞快訊】一架韓國韓亞航空公司的波音777客機(jī)6日在美國舊金山機(jī)場降落時墜毀,，目前已經(jīng)確認(rèn)該機(jī)上有141名中國人,，77名韓國人，以及61名美國人,。據(jù)外媒最新報道,，目前該客機(jī)墜毀已導(dǎo)致2人死亡，80多人受傷,。

韓亞航空是韓國的一家主要航空公司,，成立于1988年2月，原名“首爾航空”(Seoul Airlines),，員工約9600人,，目前包括貨運(yùn)航線在內(nèi)的通航目的地有百余個，航點(diǎn)以亞洲城市為主,，同時也有數(shù)條歐美航線,。

根據(jù)技術(shù)資料，波音777型客機(jī)設(shè)計載客量可超過300多人,，航空公司一般載客兩三百人,。資料顯示，波音777型客機(jī)近年來沒有遭遇過造成大規(guī)模人員傷亡的事故,。

客機(jī)機(jī)體在事故中已嚴(yán)重?fù)p毀。美國國家運(yùn)輸安全委員會調(diào)查組已在事故現(xiàn)場收集物證,，就事故原因展開進(jìn)一步調(diào)查,。