About 100,000 Hydro Ottawa customers are still without power a day after two twisters ripped through the area and neighbouring Quebec — and the city's mayor is warning residents it could take days to fully restore service to those neighbourhoods hit hardest by the storm.

In addition to destroying some of the city's electrical infrastructure, the tornadoes sent five people to local hospitals — two are in critical condition, one is in serious condition and the other two are stable. Others in neighbouring Gatineau, on the Quebec side of the Ottawa River, were also transported to hospital with injuries.

Speaking to reporters Saturday, Ottawa Mayor Jim Watson said the storm has plunged large swaths of the city into darkness after the Hydro One-owned Merivale substation was badly damaged by high winds, disconnecting parts of the city from the provincial transmission grid.

Watson said the Merivale substation cannot be fixed easily, meaning there will be prolonged outages until crews can first clear out substantial debris and then make the necessary repairs.

"It's in the top two or three traumatic events that have affected our city [in history]," Watson said. "I've experienced nothing like this in all my life living in Ottawa.

The Hydro One-owned Merivale substation was badly damaged by high winds, disconnecting parts of the city from the provincial transmission grid. (Supplied by Hydro One)

"Literally it looks like some bomb was dropped from the area, and the aerial footage I saw, the paramedics have provided a drone ... it looks like something you'd see in a movie or in tornado alley in Oklahoma," Watson said of Dunrobin, a small community on the western reaches of the city, where residents were hardest hit.

We weren't far from home, but when we finally did make it back to the house, the foundation is what's left. - Todd Nicholson, former Paralympian living in Dunrobin, Ont.

"It looks like something from a movie scene or a war scene."

Environment Canada said Saturday the tornado that hit Dunrobin was likely an EF-3, meaning it had wind speeds of up to 265 km/h.

The second tornado was classified as an EF-2, with wind speeds of up 220 km/h and it hit the neighbourhood of Arlington Woods in Ottawa.

Electrical damage worse than the ice storm

The tornadoes caused considerable damage to dozens of homes, trees and electrical transmission towers. More than 40 homes in Dunrobin alone were flattened or destroyed, leaving a trail of debris and household goods strewn across area streets.

Todd Nicholson, a celebrated Paralympian in sledge hockey and the former chef de mission for Canada's Paralympic team, told CBC News on Saturday that his community of Dunrobin is in the throes of a crisis after the storm left "a massive path of destruction."

His home was levelled, with the storm leaving just the foundation — and, miraculously, his children's fish bowl — intact.

Twisters ripped through Ottawa area and neighbouring Quebec, flattening dozens of homes, trees and electrical towers. 0:33

"We weren't home, thank goodness. We weren't far from home, but when we finally did make it back to the house, the foundation is what's left — we've pretty much lost everything," he said. "I have got a beer fridge that's sitting in my garage — that is about the only thing that is untouched — but everything else has gone."

Nicholson said it is difficult to move about the area in his wheelchair with so much debris.

"It's tough [for my kids] they don't understand and, to be honest, I don't either. We have no say in what happens. It's like my daughter said, 'Why do tornadoes happen?' And I said, 'Well, it could be worse. There could be people shooting at each other.'"

People collect personal effects from damaged homes following a tornado in Dunrobin, Ont., west of Ottawa on Friday, Sept. 21, 2018. (Sean Kilpatrick/Canadian Press)

Also hit hard was the Craig Henry neighbourhood in city's southwest end where the normally sleepy suburban streets were a hive of activity Saturday as residents began to clean up a mess of branches from felled trees.

Members of the neighbourhood's Arlington Woods Free Methodist Church were grappling with damage to their place of worship as well as to their own properties. The tornado's winds tore through the church's brick walls and pulverized the roof.

"It's been surreal. This came very quickly and when you observe all that's happened you kind of can't believe it's happened. It's almost like you've been violated," Mike Hogeboom, the lead pastor at the church, said in an interview.

The scene was equally horrifying in Gatineau, where more than 600 people were left looking for shelter after their homes were rendered uninhabitable as a result of the wind damage.

Touched down in Gatineau, Que.

After hitting Dunrobin and skipping across the Ottawa River, the more powerful tornado again touched down in Gatineau's Mont Bleu neighbourhood, upending cars there and lifting roofs straight off homes.

"I'm still in shock. I saw it face to face, it blew my window and it exploded. I almost died because the wind came through my window and it almost took me with it," Luclaire Loutanjou, a resident of the district, said in an interview Saturday. "I've seen it on TV and movies in America but I'm like, wow, how can this happen in Canada?"

Loutanjou was taken to a shelter housed in Cegep de l'Outaouais, a local community college.

"A lot of houses are down. The cars ... our apartment is like torn apart. The roof is gone and water is going through the roof. I don't know, it's hard," an emotional Loutanjou said.

"I'm worried about all the people who are here and worried about my family, my friends, and I have a lot of homework to do because I have exams next week."

David Brousseau-Lambert said he doesn't recognize his Gatineau neighbourhood after the storm. "There was carnage everywhere. Trees fallen down, cars knocked over. My whole car's damaged too — broken windows and everything and people are just crying and panicking," he said.

There were also a number of fires reported late Friday and into early Saturday morning in Ottawa-Gatineau as a result of people burning candles for light, putting additional pressure on the already stretched first responders. Authorities urged people without power to use battery-powered devices, rather than an open flame.

A car rests under debris on Boulevard de la Cité-des-Jeunes in Gatineau. (Toni Choueiri/CBC)

Bryce Conrad, president of the Hydro Ottawa, said the storm was "devastating" to the electrical infrastructure, and damage to the grid is even worse than what it sustained from the 1998 ice storm.

"In terms of the magnitude of the damage to our infrastructure — it's bad," Conrad said.

Widespread outages in Ottawa

With the Merivale substation out of service, roughly half of the necessary megawatts the city needs to keep the lights on is out of commission.

Neighbourhoods in Ottawa's west and south — including Kanata, Nepean, Barrhaven, Stittsville, but also parts of the Glebe, Westboro and Centretown — are experiencing outages.

Drone footage from Dunrobin area. <a href="https://twitter.com/hashtag/Ottnews?src=hash&ref_src=twsrc%5Etfw">#Ottnews</a> <a href="https://twitter.com/hashtag/Ottcity?src=hash&ref_src=twsrc%5Etfw">#Ottcity</a> <a href="https://twitter.com/hashtag/OttawaOutage?src=hash&ref_src=twsrc%5Etfw">#OttawaOutage</a> <a href="https://t.co/0ocrOGwSp8">pic.twitter.com/0ocrOGwSp8</a> —@hydroottawa

"That station has been hard hit. It's down. It is being assessed. It will take multiple days to restore that station," Conrad said, asking customers to be patient while crews work round the clock.

"When that station comes back on line, power will flow. In the meantime we're trying to redirect power to try to restore power where we can but that transformer station is the problem for us at the moment — this is a multi-day outage."

In total, nearly 200 citywide outages have left 97,500 Hydro Ottawa customers without power and another 2,000 rural customers, serviced by Hydro One, are also without service.

Conrad said he did not yet have accurate estimates for when power would be restored, but it would likely occur at different times for different neighbourhoods depending on the level of damage to local infrastructure. He said he expected an update on power restoration later Saturday.

Strong winds cause massive power outages and destroy homes 1:01

In a subsequent interview with CBC News, Conrad said he has never had so many customers without power during his tenure at the municipal-owned electrical utility. He called it a "crisis" that will not be solved until that Hydro One transmission substation is up and running again, feeding power to an energy-starved local distribution system.

"This is not a go out for dinner, come home, your power will be on. This is going to take time. If you were to see the devastation at that transformer station — you will understand just how significant it is," he said.

This home was completely flattened by the Ottawa tornado in Dunrobin, a rural community in Ottawa's west end. (Jennifer Chevalier/CBC )

Beyond the Merivale substation, roughly 80 to 90 hydro poles were downed by the storm.

More than 300 traffic lights throughout Ottawa are offline as a result of the power disruptions. Drivers should treat those intersections as they would a four-way stop.

All of Ottawa's hospitals are running on backup generators until power can be restored.

Ontario premier promises resources

Ontario Premier Doug Ford will travel to the area Sunday to survey the damage, pledging all the provincial resources necessary to help the municipal government recover from the tornadoes.

"On behalf of the government of Ontario, I want to tell the people of Ottawa that my thoughts are with them as they work to recover from the tornado and storm that impacted the Ottawa area yesterday, especially to the people of Dunrobin who saw immense damage to their homes and community," he said in a statement.

Late Saturday afternoon, Prime Minister Justin Trudeau sent out a tweet thanking municipal leaders on both sides of the Ottawa River for their efforts in the aftermath of the violent storm, saying the federal government stands ready to offer assistance as required. "We're with you," he said.

Also affected were some 43,000 Hydro-Qu​ébec customers.

Quebec Premier Philippe Couillard, who is in the midst of a provincial election campaign, suspended his electioneering Saturday to travel to Gatineau to tour the widespread damage in that city. Leaders of the other parties are expected to travel to the region as well.

Hydro poles in the Greenbank/Hunt Club area of Ottawa were damaged by high winds Friday. Hydro Ottawa President Bryce Conrad said damage to electric infrastructure could take days to restore. (Leah Hansen/CBC)

Ottawa's police chief Charles Bordeleau urged residents to stay away from affected areas so as to avoid injury.

There are shelters available in the city's west end for affected residents, including emergency reception centres at the West Carleton High School for those in the Dunrobin area and at the Canterbury Recreation Centre for people living in the Hunt Club-Riverside area.

Watson, the mayor, said the city does not require volunteers in the storm-damaged areas as they are well-staffed with emergency responders. Later this weekend, however, Watson said the city would set-up a hotline through which residents can make donations to help people affected by the storm.