"Somebody driving by saw two of them outside, one on the road and one on the driveway, and we got down there in a very short period of time," Durham Regional Police spokesman Dave Selby said Monday.
One of the children had little clothing — just a diaper — and the other was not dressed for "the winter weather that was out there" on Sunday morning, Selby said.
The children did not appear to have been outside for long before officers arrived, Selby said, adding that "they certainly didn't look like they were suffering too many ill effects from the cold."
Shortly after officers arrived a third child came out of the house prompting them to enter the home, where they found the children's father sleeping on a coach amid what police describe as "complete squalor."
A 23-year-old Oshawa man, whose name has not been released to protect the identity of the children, has been charged with three counts of not providing the necessaries of life.
The children are now with Children's Aid Society.