Updated at 5:20 p.m. ET
SAN FRANCISCO Investigators trying to determine why the back of a stretch limousine burst into flames on a San Francisco Bay bridge, trapping and killing five women inside, say the vehicle was carrying too many passengers.
"This particular vehicle was licensed to carry eight or fewer passengers. As we know, there were nine people in this vehicle," said California Highway Patrol Capt. Mike Maskarich.
Maskarich said the cause of the blaze remains under investigation. He did not comment on whether the overcrowding may have been a factor in the women's deaths.
The tragic incident happened Saturday night on a San Francisco Bay area bridge. The Lincoln Town Car was carrying a newlywed bride and eight of her friends, who were celebrating her recent wedding.
The driver of the limousine says he at first misunderstood what one of the passengers in the back was saying when she complained about smelling smoke.
Orville Brown told the San Francisco Chronicle that with the music up he initially thought the woman was asking if she could smoke. Seconds later, he said the women knocked again, this time screaming, "Smoke, smoke!" and "Pull over."
Brown pulled to the side of a San Francisco Bay bridge to check. As he got out, the back of the vehicle became engulfed in flames.
He helped four of the surviving women escape through the partition. One of the women ran around to the passenger door on the back side of the limo, but by then it was engulfed in flames.
"When she opened that back door, I knew it wasn't a good scene," Brown said. "I figured with all that fire that they were gone, man. There were just so many flames. Within maybe 90 seconds, the car was fully engulfed."
The newlywed bride and eight of her friends were still inside, but passersby quickly pulled three from the burning Lincoln Town Car.
"Three good Samaritans happened on the incident but were unable to get the five victims out of the limousine," said Maskarich.
The five were found dead as firefighters doused the vehicle -- all huddled near the partition, apparently unable to squeeze through.
Investigators have done preliminary interviews with survivors and the driver but need to re-interview them, Maskarich said. It will take a few weeks for investigators to piece together "some semblance of answers for the tragic events that just occurred," he said.
Debris or any other objects on the roadway do not appear to have been a factor, added Maskarich.
San Mateo County Coroner Robert Foucrault said they doubted that the blaze involved criminal activity. His office planned to begin autopsies later Monday.
Rosalyn Bersamin told CBS San Francisco station KPIX-TV one of the dead was her sister, Neriza Fojas, 31, a registered nurse from Fresno who recently wed and was planning to travel to her native Philippines to hold another ceremony before family. Her friends in the limousine were fellow nurses.
"My guess would be they were trying to get away from the fire and use that window opening as an escape route," said Foucrault.
Brown said he wishes he could have done more.
"It's something you never imagine will happen," he told the Chronicle. "It's a limousine ride. It's supposed to be a joyous thing."
Brown said he is an experienced commercial driver who has operated airport shuttles and trucks.
He started driving for Limo Stop two months earlier and had put in about six shifts behind the wheel of the Town Car that caught fire, he said.
The company issued a statement saying it "will do everything possible to investigate and assist authorities in determining the cause of this fire in order to bring forth answers and provide closure to (the) victims and their families."
According to records from the California Public Utilities Commission, which regulates limousine companies, Limo Stop is licensed and insured.