Three children in three separate areas of the city were found locked in boiling cars on Wednesday as temperatures rose into the mid-thirties.
A four-year-old boy was accidentally left inside a family car in Thornhill, Ont.
Vaughan fire officials told CTV News the child may have been spared because the car was parked in a shaded area.
A two-year-old child in New Market and a baby in downtown Toronto near Ryerson University were also found locked in vehicles on Wednesday.
Both children were quickly rescued and escaped without lasting injuries.
Accident or not, emergency officials contend it only takes a few minutes for a hot car to turn dangerous.
Dehydration and brain damage can occur within 10 minutes as temperatures can rise to 150 degrees Celsius inside vehicles.
"With this kind of weather, you can't leave your kids in the car for even a minute," Andrew Kostiuk, division commander with Toronto Fire Department, told CTV News on Wednesday.
"Even if you think you're going to run in and do something really quick and get back to the car in a few minutes, you may be delayed for reasons unsuspected."
With a report from CTV's John Musselman
