Who killed me?(Part 2 in sires)

I was auditioning for the school play. I was on stage alone in front of the whole drama clud. As I began to sing a gun appeard from behind the curten and shoot. I died. The gun was found but only the gun.

1)The killer doesn't have to be near the gun to use it 2)It could have been any one of the 20 in the room but the teacher.