The fire that engulfed a limousine on a bridge over the San Francisco Bay in May -- killing five members of a bachelorette party , including the bride-to-be -- was the result of friction between the car 's drive shaft and the rear floor board , investigators said Monday . They ruled the fire an accident and said no criminal charges will be filed . Nine passengers were traveling in the limousine as it crossed the San Mateo-Hayward Bridge on night of May 4 , including 31-year-old Neriza Fojas , who was celebrating her upcoming wedding . Driver Ricky Brown told CNN two days later that as he drove over the bridge , one of the passengers knocked on the partition separating him from the back and said `` smoke . '' He thought she was asking to smoke a cigarette , he said , so he told her to wait just a few minutes because smoking was n't allowed inside the vehicle . After 30 seconds , she knocked again , Brown said . That 's when he smelled smoke and pulled over . Cell phone video shot by another driver shows the limo at the side of the bridge , the back engulfed in flames and the front in smoke . A `` catastrophic failure '' of the limousine 's rear suspension system allowed the rapidly spinning drive shaft to come into contact with the floor pan , Capt . Mike Maskarich of the California Highway Patrol 's Redwood City office said . As the fire grew , it ignited the back seat , creating black smoke and flames that filled the passenger compartment , Foster City Fire Chief Michael Keefe said . The smoke and fire blocked access to the rear doors , leaving passengers with only one exit -- the small opening into the driver 's compartment , he said . San Mateo County District Attorney Steve Wagstaffe said Monday his office looked for anything that could have constituted a crime but found nothing . `` We 've explored all possibilities , and the conclusion is that this is a horrific tragedy , '' he said . Whatever went wrong with the suspension system happened after the limo started crossing the bridge , investigators said . Video of the vehicle going through the bridge 's toll plaza does not show it riding low to the ground . The investigation showed , however , that the limousine was carrying two more people than allowed . It was rated for seven passengers but was carrying nine . The owner of the limousine company will be fined $ 7,500 for failing to operate safely , because there were n't enough seat belts for all nine passengers , said Brig . Gen. Jack Hagan , director of the safety and enforcement division of the California Public Utilities Commission , which oversees passenger carriers like limousines .
The limousine 's suspension system suffered a `` catastrophic failure '' It created friction between the drive shaft and the floor board , igniting a fire . Five members of a bachelorette party were killed , including bride-to-be Neriza Fojas .