The GUNS N' ROSES guitarist was in New York City recently, and decided to take time out to surprise the young cast members while they were practicing his band's classic Sweet Child O’Mine.

The cast was stunned by his appearance, and after calming their excitement down, managed to pick up their instruments again as Slash joined them to perform Paradise City.

Slash, who also took pictures with each young actor, praised the kids' musical talents, telling Rolling Stone, "It was really cool to meet such an enthusiastic and talented bunch of young rock 'n' rollers. They were great kids as well as players."

Slash's surprise appearance comes months after Fleetwood MAC frontwoman Stevie Nicks also joined the cast to cover her band's song Rhiannon.

School of Rock, based on the 2003 Jack Black film of the same name, features music by Andrew Lloyd Webber and a book by Julian Fellowes.