Crews worked overnight to re-rail the eighth and ninth cars of a 10-car train bound for San Francisco International Airport, where they derailed after departing Concord Station at around 9:20 a.m., spokesman Linton Johnson said.
About 65 passengers were on board at the time, and three people complained of back pain after the derailment, Johnson said.
Repairs to the transit system's third rail were also made overnight.
The derailment remains under investigation.
