Most of the shootings were in downtown Langley, a town of 26,000 about 48 kilometres southeast of Vancouver. One reported shooting was in neighbouring Langley Township.
Police offered no immediate word on the suspect's motive or identity.
Sergeant Rebecca Parslow of the Royal Canadian Mounted Police said she had no details on the conditions of the victims.
After the shooting began, ambulances and police vehicles converged at a mall. The area was cordoned off with yellow police tape, and a major intersection was closed. A black tent was set up over one of the crime scenes.
An unmarked police SUV at one of the shooting scenes had at least seven bullet holes in the windshield and one through the driver's window.
Police issued a cellphone alert at about 6:30 am local time (3:30 pm CET), telling people to avoid the area and describing the suspected shooter. Another alert later said that the suspect was in custody and was believed to be solely responsible for the attacks.
A homicide team confirmed on social media that its investigators deployed to Langley to help.