An autopsy has been completed on a toddler a day after he was left unattended in a car in Milton, Halton regional police say.

“The findings at this time are consistent with the ongoing police investigation of the child being exposed to high-level temperatures for an extended period of time in an unattended vehicle,” police said in a release on Thursday.

The two-year-old boy was in the care of his maternal grandmother when he died on Wednesday afternoon at Jempson Path in Milton. The child’s father was at work and the mother was on an errand at the time.

The victim had a five-year-old sister who was at school at the time and remains in the care of her parents.

Research shows that cars heat up very fast with the biggest spike happening in the first 15 to 30 minutes, police say.

So far this year, 15 children in the U.S. have died of vehicular heat stroke, according to kidsandcars.org. Last year, 32 children died of vehicular heat stroke.

The organization said in an email the two other stats it has for Canada date back to the early 2000s.

On June 7, 2004, two-year-old Noah Gaudet died after playing hide and seek and getting into the family’s SUV on his own.

In 2003, Audrey Martin, 23 months, died after she was left in the parents’ car instead of being dropped off at daycare.