SAN FRANCISCO -- (CNN) Two people died and one passenger is unaccounted for after a Boeing 777 from South Korea crashed Saturday upon landing at San Francisco's airport, sending up a huge fireball, shedding its tail and spinning before screeching to a stop.
Asiana Airlines Flight 214 left Seoul's Incheon International Airport earlier Saturday, according to FlightAware, a website that offers tracking services for private and commercial air traffic. An airline spokesman in Seoul told CNN that 291 passengers and 16 staff members were aboard.
Two people have died, San Francisco Fire Chief Joanne Hayes-White said. NBC news reported 181 injured and one person unaccounted for.
PHOTOS | Boeing 777 crashes at San Francisco Int'l Airport
At least eight injured adults and two children at San Francisco General Hospital are in critical condition, said San Francisco General Hospital spokeswoman Rachael Kagan.
Anthony Castorani, who witnessed the landing from a nearby hotel, said he saw the plane touch the ground then noticed a larger plume of white smoke.
"You heard a pop and you immediately saw a large, brief fireball that came from underneath the aircraft," he told CNN.
Kristina Stapchuck saw the dramatic scene unfold from her seat on a plane on the airport tarmac. Soon after Flight 214 touched down, "it looked like the tires slipped a little bit and it rocked back," she told CNN.
Video taken soon after the crash and posted on YouTube showed dark gray smoke rising from the plane, which appeared to be upright. That smoke later became white, even as fire crews continued to
The top of the aircraft was charred and, in spots, gone entirely, according to video from CNN affiliate KTVU. The plane was on its belly, with no landing gear evident and the rear tail of the plane gone.
Debris settled from the water's edge, along San Francisco Bay, up to where the plane eventually came to a stop.
Fire trucks were on site; first responders could be seen walking outside the aircraft.
Evacuation slides could be seen extending from one side of the aircraft, from which there was no apparent smoke.
According to Asiana Airlines, 141 of the passengers who were aboard Flight 214 are Chinese, 77 are South Korean and 61 are American.
The Bay Area airport was closed to incoming and departing traffic after the crash, the Federal Aviation Administration said on its website, adding that the time when it's expected to reopen is unknown.
Flights destined for San Francisco's airport -- known by its call letters, SFO -- were being diverted to airports in Oakland, Sacramento, San Jose and Los Angeles, said Francis Zamora from the San Francisco Department of Emergency Management.
There were a few clouds in the sky around the time of the crash, and temperatures were about 65 degrees, according to the National Weather Service. Winds were about 8 miles per hour.
The National Transportation Safety Board is sending a "go team" that will be led by chairwoman Deborah Hersman to investigate the crash, the agency said. Boeing is "preparing to provide technical assistance" to investigators, company spokesman Miles Kotay said in a statement.
"We have not determined what the focus of this investigation is yet," NTSB chairwoman Deborah Hersman said shortly before leaving Washington for San Francisco to lead her agency's probe. "Everything is on the table at this point."
There are no signs of terrorism related to the crash, a national security official told CNN. President Barack Obama was at Camp David when he learned about the crash, a senior White House official said.
Asiana Airlines -- one of South Korea's two major airlines, the other being Korean Air -- is investigating the cause of the crash, a company spokesman told CNN.
The airline received the plane involved in the incident in 2006, according to the Aviation Safety Network. The aircraft has two Pratt & Whitney engines, it said.
Asiana operates many of its flights out of Incheon International Airport, which is the largest airport in South Korea and considered among the busiest in the world.
According to information on Asiana Airlines' website, the company has 12 Boeing 777 planes. The airliners have a seating capacity of between 246 and 300 people and had a cruising speed of 555 mph (894 kph).