Contra Costa County firefighters responded to a call at 1:26 p.m. of a collision involving a vehicle and a pedestrian at Solano Way at Grant Street.
They discovered that the boy, 14-year-old Concord resident Joey Hornsby, had been walking across Solano Way in a crosswalk when a 2004 Scion traveling west struck him, police said.
The boy was transported to John Muir Medical Center and later transferred to Children's Hospital Oakland.
The intersection was closed for several hours while police investigated. The driver is not believed to have been drunk or speeding, police said.