After two students were injured during a shooting at a high school in North Philadelphia, police have announced that they are making progress in terms of tracking down and vetting the three male suspects thought to have been responsible.

Philly.com reports that the shooting took place shortly before 3:30 p.m. EST inside the gymnasium of the Delaware Valley Charter High School in Logan, Penn. Two students, one male and one female, sustained non-life threatening injuries and were taken to a local hospital.

According to a report from CBS News, surveillance video from inside the school showed that approximately seven students were in the gymnasium when the shooting took place. It's not yet known whether or not the tragedy was intentional.

At a news conference on Friday, Police Commissioner Charles Ramsey announced that officers had tracked down one of the suspects identified from the surveillance video outside of his home about one hour after the incident occurred. The suspect, a 17-year-old male, was taken into police custody. He was later released after being "completely cleared by investigators," according to Police Lt. John Stanford.

According to Ramsey, a second suspect turned himself into the Northwest Detective Division for questioning later on Friday afternoon. The third and final suspect is still at large and being sought by law enforcement officials. According to reports, police have not yet disclosed which of the remaining suspects they believe to be the gunman.

"Investigators are sorting through video -- slowing it down, taking a look -- and conducting interviews to make sure we get everything all squared away before we say which one is the actual shooter," Stanford told reporters.

According to a CNN report, authorities maintain that they don't know why the shooting occurred.

"We don't know the motives," Ramsey told reporters. "Don't know if it was an accident, don't know if it was intentional."

The weapon used in the shooting was not recovered on school property by investigators responding to the scene. As of late Friday night, police continued to search for the gun along railroad tracks and other areas around a nearby transit center, according to local transit spokesman Andrew Busch.

The Friday afternoon shooting in Philadelphia is the second of two school shootings that have occurred in the U.S. this week. On Tuesday, a 7th grader in New Mexico walked into his middle school gymnasium and opened fire on a crowd of students, injuring two classmates.

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