A large indoor riding arena near Shelburne, Ont., was sheared into pieces that were strewn more than a kilometre away in a Thursday evening weather event that Environment Canada is now probing as a possible tornado.

CBC's Trevor Dunn reported on Friday morning that a sudden burst of rain and high winds arrived at about 5:30 p.m. ET Thursday and tore apart a large indoor horse-riding barn near Highway 10, just northwest of Shelburne. Shelburne is about 100 km northwest of Toronto.

shelburne, ON

"On one side of the highway, just a single wall of the barn is left standing," Dunn reported. "On the other side of the highway, the rest of that barn — torn and wrinkled sheet metal and shattered wooded trusses — is all strewn across an open field, some pieces are as far as a kilometre away."

Horses 'started to run around like crazy'

Dunn spoke with John Purdy, owner of the barn destroyed in the storm that he's convinced was a tornado.

"We had a really strange sky coming in," said Purdy. "The horses in the field started to run around like crazy, so my wife went out to bring those horses in. Within about three minutes of that there was driving rain here, you couldn't even see the road.

"The rain was coming sideways. There was a loud boom it turns out it was the indoor riding arena, which was built in 2000. It's 100 feet by 70 [30 metres by 20]. It took it out of there like it was a twig."

An Environment Canada says it's unclear if some damage in the area, located about 100 kilometres northwest of Toronto, was caused by tornadoes or high winds.

In the town of East Gwillimbury, meanwhile, police said about 20 hydro poles were knocked down on Woodbine Ave., located between Green Lane and Davis Drive.

No one was hurt but about 200 people lost power.

OPP Const. Paul Nancekevill said the damage is consistent with a tornado touchdown.

"It looks definitely like a possible tornado when you have buildings ripped apart and roofs taken off, that's some pretty severe winds."

Environment Canada issued a special weather statement for Toronto on Friday, warning that a strong cold front will arrive bringing showers, thunderstorms and wind gusts up to 80 km/h.

With files from CBC's Trevor Dunn