SAN FRANCISCO — The head of Asiana Airlines apologized Sunday for the weekend plane crash that killed two teenage passengers.
"I sincerely apologize over the accident, and to the passengers on board and their families," Yoon Young-doo, Asiana's president, told reporters at a televised news conference in Seoul.
He described the pilots involved as "skilled" and said it could take time to determine what went wrong.
Seoul-based Yonhap News Agency said the two victims were born in 1996 and 1997 and were from China. Asiana Flight 214 originated in Shanghai and stopped in Seoul before flying to San Francisco International Airport, where it crashed late Saturday morning.
The bodies of the teens were found on the runway, said San Francisco Fire Chief Joanne Hayes-White. It was not clear whether they had been pulled from the plane or ejected.
Seoul-based Asiana is South Korea's second-largest airline.
National Transportation Safety Board investigators have arrived at the airport to investigate the crash.
Dozens of survivors were taken to hospitals. Passengers said that despite the chaos, most aboard Flight 214, which originated in Shanghai with a stop in Seoul, seemed able to exit quickly and walk from the wreckage without help.
The cause was unclear. Federal investigators were looking into whether the plane clipped a sea wall separating the runway from San Francisco Bay, according to a person involved in the investigation. Officials said there was no indication that terrorism was involved.
"We were too low, too soon," said passenger Benjamin Levy, who described looking out his window, seeing piers in the bay and thinking the piers were closer to the plane than they should have been.
The pilot of the Boeing 777 seemed to rev the engines "just as we were about to hit the water," Levy said. "The pilot must have realized [and] tried to pull the plane back up. ... We hit pretty hard. I thought the wheels were gone for sure."
Levy, a 39-year-old San Francisco technology executive who'd traveled to Asia on a business trip, heard screams as the plane, carrying 291 passengers and 16 crew members, slammed into the ground.
When emergency crews arrived, the white, wide-bodied jet was emitting black and white smoke as it sat on a stretch of brown grass near the tarmac. The tail was gone and pieces of the plane littered the runway. Flames had burned a gaping hole through the top of the aircraft.
Multiple sources said there was no reported trouble or declared emergency on the plane before it landed.
Asked at a news conference if pilot error was a factor, Deborah Hersman, chairwoman of the NTSB, said "everything's on table at this point. We have to gather all the facts before we reach any conclusions."
Hayes-White, the fire chief, said a number of passengers were seen emerging from the waters of San Francisco Bay when first responders arrived on the scene. However, the wreckage was a short distance away and Hayes-White said "the assumption" is that survivors may have immersed in the water themselves to douse flames.
Hayes-White added that when her crews arrived, emergency chutes had already been deployed "and we were observing multiple people coming down the chutes and walking to safety, which was a good thing." San Mateo County firefighters performed search-and-rescue operations inside the aircraft, she added.
On Saturday night, all 307 on board had been accounted for, authorities said. One hundred eighty-two people had been transported to hospitals, including 49 in serious condition. Among the passengers were 77 Korean citizens, 141 Chinese, 61 Americans and one Japanese, according to South Korea-based Asiana.
Flight 214, like all aircraft landing in San Francisco on the sunny clear morning, was using visual flight rules, an airport spokesman said. FBI Special Agent in Charge David Johnson said his agency will be assisting the NTSB to determine the cause of the accident.
Moments after the crash, a United Airlines pilot in another plane announced welcome news to the airport control tower: There were survivors.
"We see people," the pilot told air traffic controllers in a recorded conversation with the tower. "They need attention. They are alive and walking around."
"We can see about two or three people that are moving and ... survived," a second unidentified pilot said.
Their radio dispatches came as controllers rushed firetrucks and ambulances toward the stricken plane.
"We have emergency vehicles responding," a controller told the Asiana cockpit. "We have everyone on their way."
Passenger Jang Hyung Lee, 32, of Emeryville, Calif., said there was no announcement from the pilot or crew just before the crash, but he knew what was happening.
Belongings began to tumble from seats and storage bins and he felt gravity pushing him to the left-hand side of the plane as the right side tilted upward.
He clutched his 16-month-old son to his chest and braced for impact.
The engines revved one last time, he said, and then the jet hit the ground.
Lee felt two bumps — one less violent, the next much harder — as the plane hit the ground. Smoke began to fill the cabin. He saw flames coming from the right-hand side of the plane — small at first, then bigger.
From impact to full stop, the crash lasted 30 terrifying seconds.
Lee and his wife, with their son, flung themselves onto an evacuation chute and ran off the grass and onto the tarmac, away from the burning plane.
Levy, the San Francisco tech executive, was sitting in seat 30K, which he said was "right behind the wing on the right-hand side."
As the plane crashed, he said everything turned into slow motion.
"First of all, you don't believe it's happening," Levy said. "When the plane stopped, I realized I was going to be OK."
Levy said that as smoke billowed and screams filled the cabin, he worked to help open an emergency door and get passengers off the plane. He said most passengers "managed to get out very quickly," and that he stepped on debris as he eventually made it to the ground and fled.
He ended up hospitalized with a painful rib injury.
San Francisco General Hospital treated 52 crash victims Saturday, including 10 who arrived in critical condition. Five of those were upgraded Saturday night to serious condition, said Rachael Kagan, a hospital spokeswoman.
The hospital set up tents outside the emergency room to accommodate additional patients from the crash who didn't require trauma care, said Kagan.
"We have seen a variety of injuries you would associate with a crash or fire," Kagan said, including burns, fractures and internal injuries. Some patients needed to go immediately into operating rooms.
The Boeing 777 is a twin-engine jetliner and one of the world's most popular long-distance planes, often used for flights of at least a dozen hours, carrying passengers from one continent to another.
The most notable accident involving a 777 happened in January of 2008 at London's Heathrow Airport, when a British Airways jet made a hard landing about 1,000 feet short of the runway, breaking the landing gear. There were at least dozens of injuries, but no fatalities. An investigation into that crash said the formation of ice crystals blocked fuel from reaching the jet's engines.
Thousands of passengers were stranded at San Francisco International Airport after Saturday's crash, which shut down its runways for much of the afternoon.