A mudslide over train tracks in the Niles Canyon area of Alameda County caused a commuter train to derail Monday night, injuring nine people, an Altamont Corridor Express spokesman said Tuesday.
Investigators initially thought the obstruction was a fallen tree, but determined Tuesday morning there was a mudslide over the tracks, ACE spokesman Steve Walker said.
Two cars of the Stockton-bound train derailed at about 7:15 p.m. while it was traveling at about 35 mph in a posted 40 mph zone about a mile west of Sunol, halfway between Fremont and Pleasanton.
The first car flew off the tracks and landed on its side, partially submerged in nearby Alameda Creek. The car behind it remained upright but its wheels were buried in mud, Walker said.
Crews spent most of Tuesday putting one car back onto the tracks and hauling another one out of nearby Alameda Creek using a crane. Whether the derailed car, valued at more than $2 million, can be salvaged remains to be seen, according to Walker.
Five passengers and the train's engineer were on board the first car. Four of them were seriously injured in the derailment and were taken to a hospital. Five other people on board the train suffered minor injuries, just scrapes and bruises, Walker said.
Alameda County fire officials said a few other people had minor injuries but were treated at the scene.
Sheriff's Sgt. Ray Kelly said Monday night it was a "miracle that nobody was killed."
The other approximately 200 passengers on board the train were taken by bus to the Alameda County Fairgrounds and then to their final stations, according to the fire department. All passengers reached their final stations by about 1 a.m., ACE officials said.
The ACE commuter train, which runs from Stockton to San Jose, has had two previous derailments in its approximately 17-year history, though neither has resulted to any injuries of passengers. A train going 8 mph derailed while switching tracks near the Stockton station in 1999 and then in 2008, a slow-moving train with no passengers on board derailed in the rail yard, ACE officials said.
Since the cause of Monday's derailment is clear, the National Transportation Safety Board is not sending investigators, Walker said.
Service was canceled for Tuesday, but ACE officials said it would resume Wednesday morning.
The tracks in the area are owned by Union Pacific. Once the derailed train is removed from the tracks, they will need to be cleaned and inspected before service can resume. Union Pacific will have the final say on when the tracks are safe for regular service again, Walker said.
Union Pacific crews inspect the tracks in the area twice a week for obstructions, according to Walker.