Investigators say it appears the vehicle's rear suspension system failed, causing the body of the 1999 Lincoln Town Car stretch limo to drop onto its drive shaft, which sent sparks into the passenger compartment through a crack in the car's body.
The San Jose Mercury News said investigators believe the air shocks failed while the limo was crossing San Francisco Bay via the San Mateo Bridge.
"This unfolded very, very rapidly and the overall nature of this tragedy was not something that was foreseeable," CHP Commander Mike Maskarich said at a news conference.
The limo was carrying nine women to a party on May 4 to celebrate Neriza Fojas' wedding. Four of the women were escaped. Autopsies show Fojas and the other victims died of smoke inhalation.
No criminal charges will be filed against limo driver Orville Brown or the limo company, investigators said. The limo company, however, will be fined for transporting too many passengers, KNTV, San Jose, reported
Brown's estranged wife alleged last month that she had been arguing with him on the phone just minutes before fire erupted but officials say phone records show he was not using his cellphone at the time of the fire, Maskarich said.