A pit bull mauled two Pennsylvania children in a minivan as they sat helplessly strapped into their car seats, police said.

The 5-year-old, 66-pound dog broke through a fence, WPMT reported, and got inside the vehicle as the children's mother was securing  her 2-year-old daughter and 5-year-old son in their car seats.

Tom Grab told WPMT that he was able to pull the pit bull off the boy, who was on the ground, but it wriggled free.

“I held it for what felt like forever but it was like five seconds,” Grab said. “It was raining, so it slipped right off.

“And then it got back on the kid again before the kid could even get up.”

Witnesses said the dog seriously injured the boy’s face, WPMT reported.

The attack ended when the dog’s owner came out and secured the animal, police said.

Police said the boy is still listed in serious condition; the girl is expected to be released from the hospital soon, WPMT reported.

The dog is currently quarantined in a secured kennel at the owner’s home, WPMT reported. Once the 10-day quarantine period ends, the dog will be euthanized, police said. The dog’s owner is cooperating with the police investigation. No charges have been filed at this time, WPMT reported.