By Sarah McBride and Kristina Cooke

SAN FRANCISCO (Reuters) - Tapes of 911 emergency calls made moments after an Asiana Airlines jet crashed at San Francisco airport last Saturday reveal panic and confusion, and highlight some possible problems as emergency services raced to the scene.

The crash of the Boeing 777 killed two and injured more than 180. The first police and fire personnel arrived at the crash scene in about two minutes, and local officials said brave rescue efforts and effective triage of the many wounded likely saved lives.

Still, the 11 minutes of 911 tapes released by the California Highway Patrol portray a tense and sometimes chaotic situation as severely injured passengers awaited help.

"There are people laying on the tarmac with critical injuries, head injuries. We're almost losing a woman here," one passenger said in a taped call, stating she had been waiting for 20 to 30 minutes.

The tapes appear to confirm witness accounts that several people were left unattended near the end of the runway as emergency crews focused on the main crash site.

"We have people over here who weren't found," another 911 caller said.

Three flight attendants and one Chinese student, who died in the accident, were ejected from the back of the plane after the tail broke off, according to National Transportation Safety Board Chairwoman Deborah Hersman.

Officials are also investigating whether one of the two Chinese teenagers killed in the crash was run over by a fire truck, according to the San Francisco Fire Department. The large number of non-English-speaking passengers also presented some unexpected problems.

"We're looking at this, and what we can learn from it," Rob Dudgeon, deputy director of the department of emergency management at the city and county of San Francisco, said in a phone interview on Thursday.

'SOMETHING OUT OF A NIGHTMARE'

At a news conference on Monday, police and firefighters described a dramatic scene of running up an emergency escape chute to board the burning aircraft, handing out knives so crew could cut trapped people free, and tearing away seats and luggage to clear choked exit paths.

"It was like something out of a nightmare," said San Francisco police officer Jim Cunningham, describing a plane cabin filling with thick black smoke as rescuers worked to free a few trapped passengers even after most had gotten off safely.

The call to evacuate the plane was made 90 seconds after it came to a halt on the runway, Hersman said on Wednesday. The crew first told passengers to remain seated, but an evacuation began after a flight attendant reported seeing fire outside the plane.

The NTSB will examine whether proper evacuation procedures were followed, Hersman said, adding that "hindsight is 20/20."

Some passengers on the taped 911 calls reported not seeing ambulances and fire trucks.

But emergency responders say procedures call for not bringing vehicles too close to the scene, in order to avoid chaos and collisions. In this case, there was also a worry that the plane could explode, said Mindy Talmadge, a spokesman for the San Francisco Fire Department.

"There's active fire, and there's fuel leaking, and there's debris all over the field, the last thing you want to do is take a chance of the plane exploding," she said in a phone interview on Thursday. A fire burned through much of the plane's cabin, although Hersman said the fuel tanks did not rupture.

Dudgeon said procedures called for a methodical approach in identifying the injured, starting in one spot and working forward. That could potentially leave some victims unattended for many minutes.

"If you start to worry about go here, go there, you miss things," Dudgeon said. "As a paramedic, when you're doing triage, you start where you are. You keep moving forward until you've triaged everybody."

Naj Meshkati, a professor at the University of Southern California who studies aviation safety, said he recalled other plane crashes where passenger groups were overlooked initially.

"In this day and age that we have the GPS and the surveillance camera system, I think something should be changed and could be changed," he said, adding that overall emergency response at the crash "worked beautifully."

Some 40 to 50 ambulances were sent to the crash site, said Dr. John Brown, medical director for Emergency Management Services, San Francisco. Some left the scene with up to five injured people in them to make sure the critically injured arrived quickly at hospitals, he said.

'OVERALL, SYSTEM WORKED WELL'

The most sensitive issue for responders in the aftermath of the crash was whether they may have inadvertently caused one of the fatalities.

Robert Foucrault, coroner for San Mateo County, where the airport is located, said autopsy results on how two Chinese teenage girls died would be released in about two weeks.

Emergency personnel declined to comment specifically on the matter. Dudgeon said that generally speaking, emergency-vehicle drivers are trained to look everywhere around them. "Everybody's eyes are everywhere," he said. "It's heads on a swivel."

The triage of the injured resulted in some non-English speaking victims being separated from their families. Most of the passengers on the flight were Chinese and Korean, and it is not clear if any of the emergency responders spoke those languages.

Passenger Eugene Rah recalled helping a non-English speaker whose injured wife was sent to San Francisco General Hospital.

"He was very nervous," Rah said on Monday, adding that for several hours the man was not sure where his wife was or what condition she was in.

Medical personnel say the most important thing is to make sure the most critically injured patients get treatment as quickly as possible, even if it means separating families.

"The psycho-social issues are real, but they're trumped by the medical issues," said Chris Barton, chief of emergency medicine at San Francisco General Hospital, which received 66 injured passengers and crew.

In some cases, when uninjured Korean or Chinese children arrived at the hospital with their injured parents, the hospital admitted the children to the pediatric ward so they would have a place to stay and would not be separated from their recuperating parents, he said.

Barton and other area hospital staffers said the response by emergency personnel on the crash site was impressive, with patients arriving promptly and with initial care, such as drip systems for intravenous fluids, already handled.

"Overall, the system worked well," Barton said. "The triage, the communication."

That was not always apparent to passengers on the scene.

"There's not enough medics out here," one 911 caller said, saying a woman on the runway was "pretty much burned, very severely on the head, and we don't know what to do.

"She will probably die soon if she doesn't get help," the female caller said. "Is there any way we can assist her?"

To another caller, who said he had yet to see a fire truck, the dispatcher said, "We are responding, trust me."

(Reporting by Kristina Cooke, Sarah McBride and Alistair Barr in San Francisco.; Editing by Jonathan Weber and Peter Cooney)