SEATTLE, Wash. — University of Washington students were sent running Thursday night after a man walked into a classroom and, as part of a prank, played a pre-recorded message that said, “the C4 is charged,” followed by a countdown.

KOMO reports students pulled the fire alarm as they evacuated Savery Hall around 5 P.M., and that no one was injured.

Police quickly caught up with the man on University Way and arrested him when they found no explosive device on him or in the classroom.