REDWOOD CITY, Calif. - A stretch limousine that burst into flames on a San Francisco Bay bridge, killing five women inside, was carrying one too many passengers, investigators said Monday.

The state Public Utilities Commission had authorized the vehicle to carry eight or fewer passengers, but it had nine on the night of the fire, California Highway Patrol Capt. Mike Maskarich said. He did not comment on whether the overcrowding may have been a factor in the deaths.

The cause of the blaze remains under investigation, and the vehicle has not yet been inspected, Maskarich said.

The Lincoln Town Car was packed with young women celebrating a girls' night out with a newlywed bride when it went up in flames Saturday night on the San Mateo-Hayward Bridge. The driver and four women were able to escape.

The newlywed woman was among the dead.

The driver, Orville Brown, said at first he misunderstood what one of the passengers in the back was saying when she knocked on the partition between the passenger area and the driver compartment and complained about smelling smoke.

With the music turned 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 told the San Francisco Chronicle.

He helped the four 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 five dead were found huddled near the partition, apparently unable to squeeze through. They have not yet been identified.

Firefighters arrived within minutes and extinguished the blaze. Investigators have done preliminary interviews with survivors and the driver but need to reinterview them, Maskarich said.

The investigation was expected to take several weeks to complete, he added.

Two of the survivors were still hospitalized Monday in critical condition.