By Jericka Duncan, Elizabeth Hur

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PHILADELPHIA (CBS) – Police are investigating the shooting of two teens aboard a SEPTA Broad Street subway train Wednesday afternoon. One of the teens is in critical condition.

Eyewitnesses say students wearing the uniform of Mastery Charter School boarded the train shortly before 2 p.m. Wednesday and a large group of them immediately started fighting. Police say the fight occurred between students of rival high schools.

The witnesses say the students continued fighting as the train proceeded for two stops.

Then, while the train was stopped at the Susquehanna–Dauphin station in North Philadelphia, an estimated four shots rang out.

“Once he started shooting, everyone on that car was going crazy,” said Michael Watson, who was riding in the subway.

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According to investigators, two teens were shot, one in the leg and the other in the arm. The victims — aged 14 and 17 — were taken to Temple University Hospital by Philadelphia police officers. The 17-year-old has since been treated and released. The 14-year-old, police say, is in critical condition.

Transit Police Chief Thomas Nestel says the shooting was sparked by an argument between two groups of teens from rival schools. Police wouldn’t say which schools.

Sources say one man was taken into custody shortly after the shooting, hiding in a house on the 2200 block of N. Carlisle Street. That individual was not immediately considered a suspect.

“It was one of the deals where police were arriving and people began running. The police officers chased the people that ran. So we are holding onto those people to see what information they have,” said SEPTA Police Chief Thomas Nestel.

Southbound local service on the Broad Street subway was suspended for about two hours as the investigation continued.

Officials say they’re relying on surveillance video and witnesses to find the shooter.

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