The storm lasted only about 25 minutes on Wednesday afternoon but quickly overwhelmed drains and other infrastructure, forcing water and debris onto streets and into homes.
In the middle of the chaos, Kamloops Fire Rescue and BC Ambulance were called to pull a boy out of the Thompson River, which runs through the city.
A caller reported a boy screaming for help, but it was later confirmed he made it out safely.
Mike Adams, acting deputy chief for Kamloops Fire Rescue, said it was a chaotic few hours.
"The boy in the river, the vehicles that were stranded, people on top of the vehicles, lightning strikes, reports of fires. It's been mayhem right now."
"We've been working in partnership with other departments in the city — public works to be one of them, RCMP, BC Ambulance, Hydro, trying to co-ordinate our efforts and serve the city as best as we can."
Mike Firlotte, manager of Utility Services with the City of Kamloops, said crews were investigating the scope of the damage.
He said a similar flash flood happened two years ago but this time the flooding was more widespread.
Dan Sutherland with Kamloops Fire Rescue said crews were responding to many reports of flooding in basements.
Environment Canada said as much as 25 millimetres of rain rolled over the region.
Meteorologist Doug Lundquist said more rain is expected on Thursday but clear skies are ahead on Friday, with lot of sun expected on the weekend.
Chad Graham, from a local car dealership, said he saw vehicles that were parked on the street floating in the water.
He said the vehicles were damaged further by others that passed by. (The Canadian Press, CFJC)
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