Credit: ABC News

An Asiana Airlines flight carrying 290 passengers and one infant, according to San Francisco EMS, made an apparent crash landing on the runway of the San Francisco International Airport today.

Asiana flight 214, a Boeing 777, was traveling from Seoul, South Korea, to San Francisco, according to FlightAware.com.

A video posted on YouTube showed gray smoke billowing from the plane, which was lying on the runway on its fuselage. Chutes had been deployed from the plane's emergency exits.

Get Live Updates with ABC News' Live Blog of the Plane Crash at San Francisco Airport

Aerials of the crash, provided by ABC's San Francisco station KGO-TV, showed the plane's tail severed from its body, as well as the majority of the aircraft's roof charred away. One of the plane's wings appears to have snapped upon impact. Debris from the crash landing was scattered across the airport's runway 28.

Law enforcement official told ABC News that the crash appeared to be an accident, but that they were investigating.

A witness described to ABC News what he saw when the plane was landing.

"The nose of the plane was higher than usual for a plane coming in to land and I thought that was odd," Stephen Dear said. "It got closer and closer. I saw the back tail hit the ground."

Dear said the plane then "caught fire immediately."

Dominic Garcia, who also witnessed the crash, told ABC News that when the plane hit the runway, he saw what appeared to be "a huge mushroom cloud."

"Within 15 seconds it was just black smoke," he said. "It looked like an explosion."

Stephanie Turner, another witness, said that when she saw the plane coming in for landing, it looked as if it was approaching the runway at a strange angle.

"As we saw the approaching Asiana flight coming in, I noticed right away that the angle was wrong, that it was tilted too far back," she said. "The angle didn't manage to straighten out and the tail broke off."

Turner said when she saw the plane crash land, "we were sure that we had just seen a lot of people die."

"It looked like the plane had completely broken apart," she said. "The flames and smoke were just billowing."

Turner said that when the plane hit the runway, the tail hit first and then the plane flipped and cartwheeled onto the runway.

The Boeing 777 is one of the safest airplanes in use, ABC News aviation analyst John Nance said.

"These airplanes are over the water, over the ocean all the time and Asiana has been running them for many years very successfully," Nance said.

The last Boeing 777 to crash was a British Airways jet en route from Beijing to London's Heathrow airport, which crash landed short of the runway in January 2008. There were no fatalities, but 47 people on board sustained injuries.

The details of the landing were unclear and it is currently unknown whether there are any casualties.

Check back for updates on this developing story.