A  bicyclist who was not wearing a helmet suffered serious injuries Monday after he ran a red light and collided with a pickup truck in Bath, police said.

Police did not identify the 22-year-old man on the bike, but said he was riding a bicycle that was not equipped with brakes, said Bath Police Deputy Chief Andrew Booth said.

Witnesses told police that the cyclist was headed east, downhill, along Centre Street, when he entered the intersection with Washington Street against the light and struck a pickup truck headed north. The pickup truck driver had the right of way, police said.

Police briefly shut down the intersection to tend to the cyclist’s injuries and investigate how the crash occurred.

The cyclist was taken to Maine Medical Center in Portland.