A 24-year old concealed carry holder in Philadelphia says he was forced to shoot three teenagers in self-defense after they attacked him on a city bus early Thursday morning.

Police responded to reports of the shooting on the SEPTA bus in northeast Philadelphia and found three individuals, aged 15, 16, and 17 with gunshot wounds to their legs. The trio were transported to a local hospital, where they’re expected to recover.

Meanwhile, the concealed carry holder who fired the shots remained on scene and cooperated with police, telling officers that he was attacked by the three as he sat at the back of the bus.

Police are still working to determine what led to the altercation and shooting. Investigators said the three teens approached a 24-year-old man who was sitting in the back of the bus. For some reason, they got into a physical altercation, and during that time police said the victim ended up shooting each of the teens…

Police said the 24-year-old shooter was transported to the Northeast Detective Division for further investigation. A weapon was recovered. Investigators also said the man had a concealed carry permit and showed officers those credentials.

Officers said they found three spent shell casings on the bus.

“There were about three other people on the bus at the time who were not involved. Those three individuals were transported to Northeast Detectives as witnesses. The 35-year-old bus driver was not injured and not involved. He was driving the bus when it happened,” according to Philadelphia Police Chief Inspector Scott Small.

Unlike some cities, Philadelphia doesn’t prohibit lawful concealed carry on public transportation. In fact, open carry is also legal on SEPTA trains and buses as long as the individual is licensed to carry a firearm. So far, the 24-year old isn’t facing any charges in connection with the shooting, though the investigation does continue.

In a separate incident, Philadelphia police recently announced the arrest of a 21-year old man on murder charges following a fatal shooting on a SEPTA train on March 30th. 21-year old Tahmir Banks is accused of shooting 41-year old Nicholas Troxell in the head while on the subway, and then leaving him to die. Police say that Banks was one of a group of four or five people on the train when the shooting occurred, but so far his is the only arrest in the murder.