VANCOUVER -- A powerful windstorm caused chaos in southwestern British Columbia on Saturday, knocking out power to 400,000 homes and felling trees that crushed cars and critically injured a woman.

Winds gusting up to 80 kilometres per hour forced the closure of Vancouver's jewel, Stanley Park, although the east side of the park re-opened Saturday afternoon.

The annual Pacific National Exhibition initially said it would close, but later announced it would stay open after Environment Canada cancelled a wind warning for Vancouver.

Emergency lines were flooded with calls and police were asking people to stay home. Surrey RCMP said multiple trees fell down, crashing into cars and striking a pedestrian at around 12:30 p.m.

"There have been also been several near misses between trees and members of the public," said Sgt. Bill Parmar. "The current storm is making it very dangerous for the public and the first responders."

He said a woman was walking with her daughter when she saw trees falling. She was trying to warn other pedestrians and drivers when a tree fell on her.

RCMP said her daughter jumped out of the way, but the woman in her 40s was rushed to hospital with life-threatening injuries. Mounties were trying to identify her and find next of kin.

Abbotsford Police also warned residents to stay indoors. Metro Vancouver's transit authority, TransLink, asked riders to avoid using the system if possible.

Most of the homes affected by power outages were in the Lower Mainland, including in Surrey, Richmond, Abbotsford and the western Fraser Valley.

Spokeswoman Simi Heer said B.C. Hydro has launched its storm response plan, bringing together decision-makers into one room in Surrey to ensure efficient deployment of crews and resources.

Heer said the outages were due to trees and branches falling on power lines. Crews were working hard to repair damage, but customers were asked to be patient.

"Crews might simply have to remove a branch from a line, or they have to go in and repair the line or repair the pole," she said. "Windstorms are challenging because the degree of damage is quite varied."

Environment Canada said a significant storm swept across the south coast on Saturday before moving inland. Winds hit a peak of 117 kilometres per hour on Saturna Island, while they reached 80 kilometres per hour at Vancouver Airport.

The agency cancelled wind warnings Saturday evening for Metro Vancouver, Greater Victoria, Abbotsford and the Southern Gulf Islands. Warnings were still in effect for Howe Sound and the Sunshine Coast.

Heavy rain began to fall in the afternoon, with 40 to 80 millimetres forecast for Howe Sound, the North Shore and the northwest Fraser Valley.

Strong winds also swept through Rock Creek in B.C.'s Kootenay Boundary region, where a 44-square kilometre wildfire destroyed 30 homes earlier this month.

"Residents are advised there may be flying ash, and weakened trees in the fire area may fall," the B.C. Wildfire Service warned on its website.

"As well, debris from damaged or destroyed homes may become susceptible to the strong winds and move about."

The provincial government issued an 80 kilometre per hour speed limit from Westbridge to Rock Creek, warning drivers to watch for debris and dust.

Highway 19A between Parksville and Campbell River was closed in both directions one kilometre north of Cook Creek Road because of downed lines.

Ferries running from Victoria to Vancouver were delayed due to the stormy weather, according to B.C. Ferries.

SkyTrain service in Metro Vancouver was limited, with trains running from Waterfront to Metrotown and New Westminster to King George. Buses were running between Metrotown and New Westminster stations.