A two-year-old pitbull who ran away from home braved two days in a dim San Francisco railway tunnel before being rescued.

Caltrain operators spotted the pup named Roo on his first day in the tunnel. Looking at the dog’s unmoving body, they had assumed he had been fatally struck by a train, according to a recent social media post from the San Francisco animal care and control shelter.

On the second day, after Roo was seen moving, police officers set out on foot in the tunnel with a flashlight.

They found Roo, lying curled next to a rail track, and led the dog out of the dark into the light of day.

“He was terrified at first, then was thrilled to be rescued,” the animal shelter wrote in the post. The pup is a recent adoptee, who ran away after being “spooked”.

Fortunately, Roo was microchipped. He has since been reunited with his owner.

The San Francisco area has rallied around other dogs in distress as of late.

Menlo Park firefighters rescued a missing dog that was found swimming in the San Francisco Bay, as seagulls followed in pursuit.