REDWOOD CITY, Calif. — A limousine fire that claimed the lives of five women en route to a bridal party in May was “accidental in nature” and no criminal charges will be filed, law enforcement officials said Monday at the end of a three-month investigation.

The limousine was carrying two more passengers than was legal, and the livery company will be fined $7,500 for failing to operate safely, officials said during an afternoon news conference, but the extra passengers were not the cause of the blaze.

Foster City Fire Chief Michael Keefe said failure of the limousine’s suspension system allowed the drive shaft to contact the floorboard. Friction between the rotating drive shaft and the underside of the floor pan ignited materials covering the floorboard, he said.

 “As the fire developed, it ignited the foam padding and other material used to fabricate the rear seat,” said Keefe, one of several authorities relaying the results of the investigation. “This produced black smoke and flames into the passenger compartment at the base of the rear seat.

 “The smoke and fire blocked access to the rear doors of the limo, leaving the passengers with one possible exit -- through the small pass-through opening into the driver’s compartment,” he said. “Tragically, not all passengers were able to exit in time.”

Keefe said his department will continue to work with lawmakers and the limousine industry to recommend future safety measures, which could include driver safety training, pop-out windows, secondary exits, break-out tools, fire extinguisher requirements and retrofits to existing vehicles.

California Highway Patrol Capt. Mike Maskarich, commander of the agency’s Redwood City office, said the investigation included a thorough inspection of the 1999 Lincoln Town Car; analysis of its maintenance records and the business records of LimoStop Inc., the company that owned and operated it; and extensive interviews with the survivors.

“We have concluded that the fire was accidental in nature,” Maskarich said, adding that investigators also viewed two videos showing the limo operating safely the day of the fire. One was taken at San Francisco International Airport earlier that day. The second was taken at the toll plaza of the San Mateo-Hayward Bridge moments before the fire.

Although the limousine was licensed to carry seven passengers and one driver, nine women had piled into the vehicle en route to a party for newlywed Neriza Fojas, 31. Fojas and four of her close friends died in the blaze, and four others were injured.

There had been speculation about whether limousine driver Orville Brown may have been on his cellphone when the incident occurred, but Maskarich said phone records showed he was not talking when the fire broke out and his passengers called out for him to stop.

The women’s deaths as a result of smoke inhalation were “near instant,” San Mateo County Coroner Robert Foucrault said, and their suffering was “minimal.”

“This is a horrific tragedy,” San Mateo County Dist. Atty. Stephen Wagstaffe said. “It changed lives forever. But it is not a case that goes to the criminal courts.... This is a tragedy that is not a crime.”

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