Hydro One says customers in the Midland area and Peterborough were without power after a line of severe storms moved across the regions.
About 6,000 customers with other electricity suppliers in the Midland area were without power.
Officials in Midland say Smith’s Camp was hit by a severe storm shortly after 6:30 Tuesday night, inflicting widespread damage.
Only minor injuries are reported after a suspected tornado tore through a trailer park in central Ontario.
Mayor of Midland says 40 homes were “destroyed” and four factories damaged.
“I got a call shortly before seven that all hell broke loose,” Mayor Downer saids, saying an evacuation shelter has been set up at a recreation centre.
"It missed my side of town but it hit the south side, and I got a call shortly before seven that all hell broke loose," said Mayor Jim Downer, who declared a state of emergency.
"I can tell you, as a mayor I’m very proud to see my community come together in a time of crisis, people working together, and (caring) about each other, it makes the community closer."
An evacuation shelter was set up at a recreation centre, and the Salvation Army was on hand to assist.
"We’re feeding them there," said Salvation Army spokesman Jeff Robertson. "I think they had some ham sent over."
Forty homes were "destroyed" and four factories damaged, Downer said.
While an air ambulance was dispatched from Toronto a spokesman said it was cancelled "due to minor injuries."
Jackie McLauchlin, spokeswoman for Georgian Bay General Hospital, said about 20 people were brought into the hospital with storm-related injuries, but none were admitted.
"Incredibly lucky," she said.
Brad Elliott, who lives in the trailer park, said his trailer was spared — save for the skirt being blown off. Other trailers were flipped on their sides, or missing from their spots.
"It just looks like a bomb went off," he said.
"There’s stuff wrapped around trees you wouldn’t even think could wrap around a tree, like pieces of steel, metal."
Two major events in one day had Elliott shaking his head.
"Quarter to two today, you could feel the earthquake — and then this, in Midland," he said.
"Nothing ever happens here."
A woman reached at the camp says it was the seasonal section that was hit, not the mobile homes.
"The owner’s son came up and said a tornado had gone through and damaged the summer camp," said the camp employee, who only wanted to be identified as Karen.
"So there are about 50 to 60 trailers that are damaged, crushed."
Emergency Management Ontario urged people in the areas bordered by Penetanguishene to the north, Barrie to the south, Collingwood to the west, and Orillia to the east to immediately take shelter from the storm.
Red alerts were later issued for the Windsor area of southwestern Ontario and the Peterborough and Lindsay areas east of Midland.
The red alert required everyone in the area, including motorists and boaters, to go indoors immediately.
Jay Dorion at a busy Boston Pizza near the trailer park said the storm went through quickly.
"It went right beside our building, it was crazy," he said.
A few transport trucks on the highway were knocked over and the trees around the restaurant were bent over, he added.
"It didn’t look that dark and then it got really dark, and the wind picked up, and the rain picked up and you couldn’t see outside," he said.
There were also reports of funnel clouds near Orillia, Ont.
The tornado warning for Orillia and Washago was called off shortly before 9 p.m., but warnings for the Peterborough area, and regions east, carried into the night.
Sandy, who answered the phone at Scully’s Crab Shack in Midland, was frantically dealing with the storm’s aftermath.
"Oh geez, nobody has power in Midland except for me," she said, sounding out of breath.
"I saw a Honda (dealership) down, all their cars and all their windows smashed out… I heard from other people that houses and windows (were) knocked out," she said, saying she had to go, and quickly hanging up.