Investigators Wednesday tried to determine if a jammed accelerator or human error sent a commuter bus roaring through a rush-hour crowd, killing three and injuring 15.
Horrified witnesses screamed helplessly as the bus mowed down pedestrians and smashed through trees, parking meters and newspaper racks before stopping in a pile of concrete, splintered wood and twisted metal during the Tuesday evening rush hour.
At San Francisco General Hospital, spokeswoman Gloria Rodriguez said Marsha Gentry, 39, of Castro Valley was in critical but stable condition Wednesday with multiple fractures. Mary Webster, 30, of Oakland was listed in fair condition with a broken arm and leg.
An investigation task force set up Wednesday includes the California Highway Patrol, San Francisco police and district attorney's office and National Transportation Safety Board.
Police Chief Frank Jordan said the cause of the accident appeared to have been mechanical failure or failure by the driver to properly operate the gas pedal. Drugs or alcohol did not appear to be involved, he said.
Bus driver Salvador Orogo, 53, of San Francisco told police that the "accelerator stuck."
The bus had been inspected by Greyhound mechanics and the driver hours before the crash, and the accelerator was not sticking at that time, said Aubrey M. Lumley, marketing manager for the San Mateo Transit Authority, which owns the bus. The bus had undergone a CHP safety inspection last September, Lumley said.
Greyhound maintains the buses under contract to the transit authority, which runs commuter buses between San Francisco and the peninsula to the south.
Orogo, a former security guard who worked for seven years as a bus driver in the Philippines, received four weeks of training from Greyhound, including 22 hours of driving commuter passengers while supervised by another driver. He was hired as a driver for Greyhound on Sept. 21, 1987.
State records show that Orogo had one speeding ticket in December, 1985, apparently while driving a private vehicle. He had been driving alone for the San Mateo County Transit District for a month, according to police Traffic Officer John Grizzel.
The absence of skid marks, Grizzel said, indicated that the driver may have been confused about whether he was stepping on the brakes or the gas. An inexperienced driver could be confused because the pedals are close, he said.
The recommended method to deal with runaway buses is for the driver to put the vehicle in neutral, then turn the engine off or pull the emergency brake, Grizzel said. None of those steps were taken, he added.