SAN ANTONIO -- A young boy is in critical condition after becoming trapped under his father's pickup truck on the northeast side.

Police said the father was trying to load his three kids into his standard transmission truck.

Suddenly, his 2-year-old boy released the parking brake from outside the truck and fell down, police said.

The front left tire rolled up against the boy and prevented him from breathing for a short time.

Police officials called the incident an accident.

"He was on the passenger side putting a child in a child seat and the other child just ran around the vehicle," Sgt. Tobe Whitley said. "It's very unfortunate, but I can't see any fault at this time. It will be investigated but as it appears it's just a tragic accident."

The boy was taken to the hospital in critical condition.