Damage from torrential rain and gumball-sized hail has been estimated at tens of millions of dollars in Edmonton, where the cleanup from the storm continues.

The heavy rainstorm started Sunday afternoon, dumping 150 millimetres of rain on the city. The storm blew in with little warning, flooding homes and turning roads into lakes. Environment Canada called it "a one in 200-year storm.''

It also created flooding inside Canada's largest shopping centre, the West Edmonton Mall. Around 20,000 people out for a day of Sunday shopping were evacuated.

Mall officials blamed sewer back-ups and said raw sewage flooded several attractions in the mall, such as the waterpark.

Many shop employees spent the day using wet vacuums and squeegees to clean up their stores and assessing the damage Jon Stanbridge, who works at Mr. Entertainment, one of the hardest-hit stores, says it all happened so quickly.

"All of a sudden, I hear this crack and the ceiling starts coming down and people are screaming. And then there is like this fountain in the hallway because the ceiling in the hallway started coming down too. It was scary."

"Nearly my entire book wall was toast. Lots of PA equipment at the front of the store is completely demolished. It's all under water."

Most of the stores in the mall re-opened Monday. The one main exception is the Ice Palace indoor skating ring. During the storm, crews had to smash the glass around the rink to push water through. The rink is now in a bit of a slushy mess, but mall officials say it should be ready to reopen in about a week.

Elsewhere in Edmonton, the deluge of water closed major roads, and turned intersections into tiny lakes. Mountains of hail also made the city's west end look like a winter wonderland. Snowplows were brought in to keep the drifts of hail at bay.

During the storm, Linda Hallworth got stuck in the waterlogged streets. With water rising, she and her sons were stranded and scared. That's when Aaron Slepkov stepped in.

"I think I asked if she was okay and I asked her if she wanted me to help her. She said yes. She was very happy," he remembers.

Hallworth can't believe her rescuer came along when he did.

"He didn't know me at all, he just got out of his car and he helped a bunch of people he didn't know," she told CTV News, wiping away tears of joy.

City officials said more than 500 homes suffered some flooding. But Edmonton Mayor Bill Smith insists it was not the city's fault

"It might be cold comfort to those who have flooded basements, but I do want to say the drainage system worked as it was designed to do,'' he said Monday. "I don't believe there is a system in the world that could take what Mother Nature dished out to us yesterday.''

Elsewhere, funnel clouds were spotted in Morinville, about 50 kilometres north of Edmonton, and a tornado touched down near the village of Chipman, about 70 kilometres east of Edmonton.

Severe thunderstorms were reported in central Alberta, the area between Edmonton and Calgary.

Alberta has been suffering some strange weather of late. Last Thursday, a tornado touched in downtown Grande Prairie, damaging buildings in a city that rarely sees twisters.

And on Monday, the same system that hit Edmonton on Sunday sparked tornado watches in Saskatchewan.

Funnel clouds were spotted northeast of Prince Albert, Saskatchewan, said Environment Canada. There have been no reports of damage or injuries.

"It's been a wild and wacky summer -- and it's not even half over yet," Environment Canada senior climatologist Dave Phillips told Canada AM.