A tornado touched down on the west side of Ottawa late Friday afternoon, leaving as many as 30 people injured - five of them in serious or critical condition.
In one particularly hard-hit area - Dunrobin - up to 60 buildings were damaged, some of them completely destroyed.
Many people told the Canadian Press they received emergency alerts on their cellphones, advising them to seek shelter. Some made it down to their basements but came up to find their homes had been damaged.
One man in a power wheelchair told NEWSTALK1010's Ottawa affiliate CFRA that as he was waiting for Para Transpo, he noticed a tree very close to him come down and his heavy wheelchair began to sway from side to side.
"Up in the Dunrobin area, they had massive loonie-sized hail," CFRA morning show host Bill Carroll told NEWSTALK1010's The Night Side on Friday evening. "A lot of times, [that] tells you a tornado is not far behind."
"We did get the warnings - I think that's the good news - we got those cellphone warnings a fairly long time ahead," he added.
The tornado crossed provincial borders into Gatineau, Quebec, where it overturned several vehicles on Highway 50, while blowing out the windows of others.
In one location, a dog - a beagle named Charlie - had to be rescued from underneath rubble. He is said to be okay.
Environment Canada confirmed just after 6 p.m. Friday that the funnel cloud was a tornado. It's expected that it will be classified as an EF-2, with winds topping more than 200 kilometres per hour.
However, Ryan Rozinskis, a severe weather meteorologist with the agency, said it will take some time before they get all the details sorted out.
"We don't have too many details yet on the strength, the width and the exact track," he told NEWSTALK1010. "We'll be sending out damage surveys [Saturday] to start to get some of the details available on that."
- With files from the Canadian Press and CTVNews.ca