Officers received several reports around 9 p.m. of a crash involving two vehicles and a pedestrian at Hillcrest Avenue and East Tregallas Road.
Witnesses said a man was crossing the street at the intersection when the two cars struck him, according to police.
Emergency responders found the victim, a 34-year-old man, suffering from major injuries and took him to John Muir Medical Center in Walnut Creek.
Police said the man remained in critical condition as of Friday evening.
No further details were immediately available.