A runaway pit bull mauled a young girl in the Bronx Wednesday morning, cops said.

The 4-year-old was waiting for a bus on Huxley Avenue near West 261st Street at 8 a.m. when the vicious canine chomped down on the girl’s face and neck, according to cops.

A woman cracked the dog on the head with an unknown object to get the girl free, police sources said.

The dog had escaped from a nearby fenced-in yard, cops said.

The girl was taken to Jacobi Medical Center where she was critical but stable, according to the NYPD.

The beast was turned over to ASPCA, cops said.

No charges have been filed against the dog’s owner.