PORTLAND (AP) – The University of Southern Maine is offering a $5,000 reward leading to the arrest and conviction of anyone responsible for the recent string of bomb threats at the school.

USM has been forced to shut down four times this semester after receiving bomb threats on Oct. 2, Oct. 3, Nov. 8 and Nov. 14.

“We’re all fed up with the disruptions to our professional and personal lives caused by the recent series of bomb threats,” said USM President Richard Pattenaude. “We’ve tried to strike a balance between ensuring public safety and minimizing the impact on our schedules.”

Bomb threats are violations of federal and state laws, Pattenaude said.