A series of thunderstorms swept through Toronto and other parts of southern Ontario Monday, leaving roads flooded, drivers stranded in some cases and four people hurt in a lightning strike.

Environment Canada issued a series of severe thunderstorm warnings and watches on Monday afternoon, some of the earliest of which applied to Toronto and areas to the north and east of the city.

Images posted to social media websites showed heavy rains, hail and lightning occurring in various parts of southern Ontario during the afternoon.

As the afternoon progressed, more parts of southern Ontario were placed under warnings and watches, including the city of Burlington.

Lying about 60 kilometres southwest of Toronto, Burlington was hit with so much rainfall that its local highways were filled with water in some places.

On Monday evening, OPP Sgt. Kerry Schmidt told CBC News Network that both the QEW and Highway 407 were having "flooding issues" in a number of areas, resulting in a series of closures.

"I've been hearing reports of water, you know, up to the tops of vehicles, people are actually swimming from their cars," he said. "So, this is certainly an area to avoid right now."

The OPP warned motorists to watch out for problems in general with Greater Toronto Area highways.

Halton Regional Police Staff Sgt. Stephanie Jamieson said that police found themselves swamped with calls at various Burlington intersections between 6 p.m. and 7:30 p.m.

"A number of the creeks and small little rivers throughout the city just got inundated with the amount of water that we received, and so unfortunately, they really had nowhere to go and a number of them crested at the same time," she told CBC News in an interview.

No injuries have been reported as a result of the flooding, Jamieson said. 

In an update shortly after 10 p.m., police said the worst remaining flooding in Burlington was along Fairview Street and New Street, while water was still pooling in front of Burlington Mall and at Upland Drive and Upper Middle Road, forcing the closing of that intersection. 

Lots of calls were placed to emergency personnel about home and basement flooding.

CBC News spotted Alf Smith, a longtime Burlington resident, standing at the side of a road where he was using a broom in a bid to clear a clogged drain.

"I've never seen anything like this — never in 38 years living in this neighbourhood," he said.

Earlier in the day, four people were struck by lightning in a Toronto park, an event that witnesses said occurred as they were sitting under a tree. The victims were said to be in stable condition after being brought to hospital.