The locomotive initially caught fire, but the flames were eventually extinguished, a Union Pacific spokesman said.
The derailment happened around 7:30 a.m. near 5th and K Street in Colton. Police and fire brigade arrived on the scene.
Union Pacific officials added that an unknown amount of diesel had been spilled.
A contracted worker who helped clean up was injured and taken to a hospital. No other injuries were reported.
The derailment occurred at a point where some tracks turn left to pass under the highway and head north, while other tracks continue east. It is not clear in which direction the train was traveling.
The cause of the derailment is still under investigation.
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