Environment Canada is investigating a possible tornado that may have touched down in Keswick, Ont., amid a band of intense thunderstorms on Wednesday afternoon.

Geoff Coulson, Environment Canada's warning preparedness meteorologist, confirmed that the agency is looking into the storm and liasing with emergency crews in the area. Coulson said that so far there are no reports of significant damage. 

Twitter user Andy Davies posted a picture of what appeared to be a funnel cloud touching down in Keswick around 5 p.m.

Coulson said Environment Canada is trying to figure out exactly when and where Davies' picture — which was tagged with the hashtag #onstorm — was taken as part of its investigation. 

While meteorologists can track storms with Doppler radar and lightning detection systems, "getting corroboration from folks at ground level can be the final piece of the puzzle," Coulson said of the storm investigation.

Severe thunderstorm watches remained in effect for some parts of the GTA into the evening, but have now ended.

Shortly before 6 p.m., Environment Canada issued warnings about a potential tornado moving across York region, north of Toronto.

"This is a dangerous tornado! It is moving across northern York region toward northern Durham region. Sunderland is in its path," Environment Canada said in its emergency statement, which has since been taken down.

In Toronto, a severe thunderstorm brought heavy rain to the downtown core. Heavy rain came down in sheets around 6:15 p.m., briefly flooding several streets including the Bayview Extension. 

The TTC also reported that Museum station was being bypassed due to flooding.