SAN MATEO, California (Reuters) - A teenage passenger on the Asiana Airlines plane that crashed in San Francisco died from injuries sustained after being run over by a motor vehicle, most likely a fire truck at the scene, officials said on Friday.

An Asiana Airlines Boeing 777 plane is seen in this aerial image after it crashed while landing at San Francisco International Airport in California on July 6, 2013. REUTERS/Jed Jacobsohn

Ye Mengyuan, a 16-year-old girl who sat toward the rear of Flight 214, survived the Boeing 777’s crash-landing but died from blunt force injuries consistent with being run over by an emergency response vehicle, San Mateo County Coroner Robert Foucrault and San Francisco Fire Chief Joanne Hayes-White said at a news conference.

“Obviously this is very difficult news for us,” Hayes-White said. “We’re heart-broken. We’re in the business of saving lives.”

Ye was one of three Chinese girls who died in the July 6 crash. More than half of the 307 people onboard the flight from Seoul were injured in the crash.

Hayes-White said Ye was struck by at least one specialized fire-fighting vehicle normally deployed at San Francisco International Airport, but left open the possibility that she was hit by more than one rig.

The coroner’s ruling settled lingering suspicions that emergency personnel racing to douse the fiery wreckage may have inadvertently played a role in the death of one the passengers.

The announcement prompted a new set of questions over the circumstances of Ye’s death and whether the first responders, who have been generally hailed for an efficient performance, could have done anything to prevent it.

It remains unclear how firefighters failed to notice Ye before she was hit, or what she did in her final minutes amidst the crash wreckage and scenes of chaos.

Fire department officials have said Ye’s body was covered by a one-foot-thick (30-cm-thick) blanket of firefighting foam when she was found. Hayes-White said on Friday she did not know whether Ye was covered in the foam at the time when she was struck by the truck.

“There was a lot of debris scattered around. It was a difficult, challenging scene,” she said.

DRUG AND ALCOHOL TESTS

San Francisco police, who are still investigating the matter, have interviewed the firefighters operating the rig and given them drug and alcohol tests, Hayes-White told reporters.

The fire chief on Friday stood staunchly by her department and said she did not anticipate any disciplinary action against the firefighters involved in Ye’s death, which she labelled a “tragic accident.”

“It was a very volatile, dangerous situation,” she said, repeatedly commending her department’s performance. “In light of that, we will take a look at our protocols and procedures. There is always room for us to evaluate and improve our response.”

The Chinese Consulate in San Francisco issued a statement on Friday saying it noted the effort made by U.S. agencies to “look into Mengyuan’s death and disclose the truth.”

“We urge the involved parties of the U.S. side to deal properly with the aftermath of Mengyuan’s death and investigate and affix responsibility for this tragic accident,” it said.

The San Francisco Fire Department’s exposure to legal liability would be greatly diminished if the police investigation concludes that firefighter negligence did not play a role in Ye’s death.

Ye was believed to have been thrown onto the runway along with another passenger when the plane’s fuselage clipped the runway, airline officials and crash investigators said last week.

Firefighters racing to the scene sprayed fire-suppressing foam at the wrecked plane, which was leaking fuel and in danger of exploding. A fire that started in the right engine grew as passengers evacuated, and ultimately consumed the flight cabin.

Both the coroner and the fire chief said it also remains unknown how Ye’s body ended up near the airplane if she indeed fell out of the airplane where it first struck the runway, far from where the wreckage ultimately came to rest.

San Francisco Mayor Ed Lee said that many lives were saved by the “quick response and heroic decisions” of the city’s emergency response personnel.

“This tragic accident is especially hard for them - and all of us - to endure,” Lee said in a statement.