Amtrak is investigating how a window on one of its trains was partially shattered as the train traveled near Richmond on Tuesday afternoon, a spokeswoman said.
Amtrak spokeswoman Vernae Graham said "unidentified objects" struck the outer pane of a train window around 4 p.m. Tuesday as the train headed toward Sacramento and was about 6 miles east of Richmond.
About 50 passengers were aboard the train at the time, but no injuries were reported, she said.
Investigators are looking into whether the objects were bullets fired from a pellet or BB gun, rocks, or something else, Graham said.
She said she did not know whether someone was seated next to the window damaged by the objects.
A conductor was notified of the incident but the train did not stop.
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