MONTREAL -- Wind gusts, sometimes as strong as 100 km/h, knocked out power lines and blew down trees across Quebec on Friday, killing at least one person and leaving hundreds of thousands of Quebecers in the dark.

More than 3,800 power outages left 740,000 Hydro-Quebec customers without electricity as of 10 p.m., including 50,000 customers on the Island of Montreal. Some may not see their power return for several days, the agency said.

As of 11 p.m. winds were beginning to weaken across the province. In Montreal, Environment Canada forecasted winds up to 30 km/h -- a far cry from earlier in the day when Pierre-Elliott Trudeau Airport in Dorval registered winds as high as 105 km/h.

Still, Hydro-Quebec crews are working through the night, and will still be repairing downed wires into early next week, the agency said.

"Our crews, before even thinking of repairing the line, sometimes they must act like lumberjacks, so there's lots of work before we can think of repairing the grid," explained Hydro-Quebec spokesperson Francis Labbé.

"We suggest the population get prepared for maybe one or two days in the dark. It's better to be prepared than not prepared enough."

Several hundred lineworkers are on the ground to restore service, the agency said.

"Some of the outages will be easy to repair, but we have so many outages that we have to spread our teams all across the province so that might complicate everything," Labbe said. 

He advised Quebecers to avoid any trees or Hydro poles they think could be weakened from the strong winds.

"We suggest that people be fully aware of the hazards that might come up. If a tree has be made fragile by the wind, some branches could fall, so if you have a doubt, just don't walk under it… don't go near," he said.

Quebec Public Safety Minister Geneviève Guilbault urged Quebecers not to go outside unless necessary. 

"It's an impressive weather system hitting Quebec," she said. "We're seeing a lot of incidents: church roofs and house roofs that are torn off or that threaten to fall. ... I'm asking people to be extremely prudent. For those who have to go outside on the road network, be careful and those who can stay at home, avoid going outside. ... Let the storm pass."

Extra police officers, firefighters and Hydro-Quebec linemen have been called in, the minister added. Many of them will work through the night as winds begin to die, she said.

Transports Quebec closed Highway 10 in Granby in both directions on Friday evening to let Hydro Quebec crews repair wires in the area. 

Debris flying in the powerful wind injured numerous people across the province. Urgences-Santé and the Montreal Fire Department says they both received nearly double the usual number of calls.

In Bromont, violent winds tore down a tree, which struck a man in the head and killing him, Bromont police confirmed.

In Montreal's Parc-Extension neighbourhood, high winds dislodged bricks from the top of a three-storey building, hitting a 52-year-old man in the head, a spokesperson for the Montreal Fire Department said. He was taken to hospital, conscious, but confused, Urgences-Santé confirmed. His injuries are considered serious. 

On Thursday, wet weather caused some floods in the city, including in the basement of a duplex in the Côte-des-Neiges borough, which saw firefighters wading in ankle-deep water on the home’s front lawn as they tried to get inside.

City workers also responded after several sewers, including on the northbound Decarie Expressway near Plamondon Avenue, overflowed due to the accumulation of leaves in the grates.

Transports Quebec warned that Highway 20 could flood again, though it escaped any major water buildup. Part of the thoroughfare has already flooded twice in the last six weeks due to generous rainfall.

Officials admit the area hasn’t yet been set up with necessary pumping stations, as they will only be ready next summer. 

Most of Quebec received 50 to 70 mm of rain, but in Estrie and the Beauce, rainfall exceeded 100 mm, according to Environment Canada.

-- with files from the Canadian Press.