The collision was reported at 10:19 a.m. and involved San Joaquins train No. 712, which was headed from Oakland to Bakersfield, Amtrak spokeswoman Vernae Graham said.
Arroyo was hit on the tracks between Market Avenue and Brookside Drive in an area that wasn't a pedestrian crossing, Graham said.
The 55 passengers and crewmembers on the train were not injured, she said.