SUNOL, Calif. (AP) -- The Altamont Corridor Expressway is back in service following a derailment east of San Francisco earlier in the week.

Nine people were injured and two still remain hospitalized.

Union Pacific Francisco J. Castillo says a mudslide most likely caused the derailment 45 miles east of San Francisco that sent the train's leading car plunging into a swollen creek. The San Francisco Bay Area has been inundated with thunderstorms in recent days that have swamped roadways and creeks.

KNTV reports Wednesday that the 5:30 a.m. train Wednesday was about half full of normal occupancy.

ACE spokesman Steve Walker says the train will travel about 5 to 10 mph through the area of Niles Canyon Boulevard, where the derailment occurred. The train was traveling 35 mph in a 40 mph zone when the derailment occurred.

Copyright 2016 The Associated Press.