SEPTA has released two photos of a man who allegedly stabbed two teenagers, leaving one in critical condition, on SEPTA's Broad Street Line subway in North Philadelphia Friday morning.

The 17-year-olds were stabbed as they rode the train around 9:11 a.m., Philadelphia Police Department Spokeswoman Tanya Little said. The stabbing happened near the stop for Olney Transportation Center, near Broad Street and Olney Avenue.

Surveillance video showed a fight breaking out on the train shortly before the boys were stabbed, a SEPTA spokesperson told NBC10. After the fight, both the victims and the suspect got off at Olney Transportation Center, the spokesperson said.

SEPTA provided two photos of the suspect pulled from surveillance video on the subway.

SEPTA

One of the boys was stabbed in the left side of his abdomen and listed in stable condition. It was unclear where the boy in critical condition was stabbed, Little said.

Both managed to walk to Einstein Medical Center, about a block away from the train station.

Police are looking for a suspect who they believe is in his 50s.