A string of powerful thunderstorms, including several suspected tornadoes, blew across southern Ontario Thursday, damaging homes, flipping over cars and killing at least one person.

The storm, including several funnel clouds, first erupted in the afternoon near Durham, Ont., which is about 150 kilometres northwest of Toronto.

"All the trees are down around my trailer," Brenda Ailles, camping at the area, told CTV News. "There were people in tents. Everything got swept away."

Meanwhile, three children were injured, possibly seriously, at the same conservation area where the fatality was reported.

Police wouldn't comment on unconfirmed reports that the fatality was an 11-year-old boy. The death occurred when a work shed collapsed under fierce winds, The Canadian Press reported.

Vaughan and Newmarket -- two communities also north of Toronto -- were also reportedly hit by tornadoes as the powerful storm system rolled eastward.

Late on Thursday, the city of Vaughan declared a state of emergency as more than 100 houses remained under evacuation, according to CP.

Vaughan's Deputy Fire Chief Larry Bentley told CTV News that the storm was unlike anything he had ever seen.

"It's a first for me, in my 29 years in fire service, to see something of this magnitude in this area."

The intense storm activity is likely the result of a recent batch of hot and humid weather in the region, according to Environment Canada.

Violent winds also tore down power lines and uprooted trees, leaving several thousand people in the province without power.

Despite several funnel cloud sightings, Environment Canada has yet to confirm that tornadoes did in fact touch down. Confirming those reports will require a thorough assessment, officials say.

As the storm cells moved eastward, Toronto, Hamilton and dozens of other towns and cities were placed under tornado warnings.

By 8:20 p.m., a tornado watch was issued for Peterborough, Ont., which is about 120 kilometres northeast of Toronto.

An hour later, the system appeared to be losing steam as communities near Kingston, Ont, were placed under severe thunderstorm warnings, but not tornado warnings.

Widespread destruction

Over the course of the evening, there were reports that funnel clouds brought fierce winds which spun vehicles, uprooted massive trees and damaged homes.

Heavy rain was also reported, and images broadcast on CTV News Channel showed heavy flooding in some areas of Toronto.

"A line of severe thunderstorms is moving eastward through the regions. Tornadoes are associated with some of these storms," Environment Canada said on its website.

"This is a warning that severe thunderstorms with tornadoes are imminent or occurring in these regions. Monitor weather conditions. Take immediate safety precautions."

Environment Canada meteorologist Geoff Coulson said at least three buildings in Durham sustained damage by about 4 p.m. He also said there may also be damage in Markdale, which is northeast of Durham.

The warning area intially extended from Windsor, north to the Bruce peninsula. Storm activity earlier on Thursday uprooted trees and downed power lines in Sarnia.

At 4:27 p.m., the warnings had been extended to the Waterloo-Wellington, Dufferin-Innisfil, Barrie-Orillia, and most of cottage country, with the exception of the Haliburtons.

By 5:43 p.m., the warning area included York-Durham, Halton-Peel, Hamilton and Simcoe-Delhi among others.