Michael Winter

USA TODAY

Security cameras recorded two Philadelphia students being shot and wounded by a classmate in a high school gymnasium Friday afternoon, police reported.

Two teens were in custody Friday night, but police were still seeking a third student and the weapon.

A boy and a girl, both 15 years old, were shot with a handgun about 3:30 p.m. at the Delaware Valley Charter High School in the Olney section of North Philadelphia.

Police Lt. John Stanford said at a news briefing that each victim was hit once in an arm, and they were taken to Albert Einstein Medical Center, two blocks away. The girl was discharged hours later, and the boy was listed in stable condition.

Surveillance video showed three youths together and one pulling out a handgun. But Police Commissioner Charles Ramsey said it was not yet clear which one pulled the trigger, how many shots were fired or whether the shooting was intentional or accidental.

Seven students were in the gym at the time.

The wounded girl went into the bathroom moments afterward, and there was "just a lot of blood gushing out.," a friend told WPVI-TV.

"She was saying she heard a loud boom in the gym room and she looked up her and her boyfriend's arm had been hit," the friend said.

The school, for grades 9 through 12, was placed on lockdown. The 600 students were searched and released individually. Police initially believed the shooter was still inside the school but said later that he had fled, prompting a search by officers and SWAT teams.

The school is equipped with metal detectors, and police and school officials are trying to determine how the suspect got the gun inside.