Environment Canada issued a severe thunderstorm warning and tornado watch at 6:29 p.m. on Friday for Ottawa, Gatineau, and surrounding areas. On Saturday, Quebec Premier Philippe Couillard said, "we are concentrating on people, getting people back home as soon as possible, as safely as possible". "We're here to reassure everyone in the region that's been affected that we'll spare no expense, we'll do whatever it takes to make sure we get people back on their feet". "I have got a beer fridge that's sitting in my garage - that is the only thing that is untouched - but everything else has gone", Ottawa resident Todd Nicholson told the Canadian Broadcasting Corp.
The national weather agency said a powerful twister - with winds that reached 265 kilometres per hour - ripped through Dunrobin, about 35 kilometres west of the downtown area, before moving on to Gatineau.
"We're putting the resources in, we are going to get it done", he told a sobbing woman seeking refuge at the school.
A freelance journalist says a group of people rescued a dog who was trapped under the rubble in an Ottawa neighbourhood ravaged by a tornado.
Thousands of people were left without power following the monstrous storm.
The tornado also struck the house that Brian and Nicole Lowden had been renting as they built their permanent home in nearby Constance Bay.
Prime Minister Justin Trudeau also tweeted Saturday day that he'd spoken with the mayors of Ottawa and Gatineau to offer federal assistance.
"We're monitoring the situation and thinking of everyone affected", he said on Twitter.
The roofs were torn off a school and several apartment buildings, he said, estimating about 1,500 people have been displaced.
The agency said that at nearly the same time a second, slightly less powerful twister, touched down in the south Ottawa neighbourhood of Arlington Woods.
"Just as we went past the stairs, the door blew open [and] a massive four-by-four came flying through the door", said Lowden, a local paramedic.
He says the Greater Toronto Area saw wind gusts of up to 80 km/h.
Hydro crews - including extra workers from across Ontario - were working around the clock to untangle and fix fallen power lines and restore electricity to the region.
"We have all available crews out in the field", the utility company said. "They're working in unsafe conditions and, at times, are not able to start repairs until the wind weakens".
The power outages are the result of two tornadoes that wreaked havoc in the area.