A student was wounded when a boy hurled a knife at him during a fight inside an Upper West Side school.

The unidentified 14-year-old student had been fighting with another inside West Prep Academy on West 77th Street near Columbus Avenue about 1 p.m. when a 12-year-old rival hurled a switchblade, cutting the teen’s shin, police said.

The armed assailant was taken into custody by police at the scene. The victim was taken by ambulance to St. Luke’s Roosevelt Hospital where he was being treated for a cut to the leg, said a law enforcement source.

The weapon was recovered, cops said. Charges are still pending against the young attacker.

The school is a public school for grades 6 thru 8, according to the NYC DOE website. It’s not known what sparked the bloody fight.