WALES — Oak Hill High School will reopen Friday after State Police and K-9 units searched the building Thursday morning after the discovery of a threat scrawled on a bathroom wall Wednesday.

Regional School Unit 4 Superintendent Andrew Carlton sent out a note Thursday to parents saying the school would reopen Friday, but that all Thursday evening activities, including a planned musical concert, were cancelled and would be rescheduled.

Carlton said representatives of the State Police and the Sabattus Police Department will be at the school all day Friday for added security.

“I appreciate your patience with us as we have investigated this matter. We take student safety very seriously and it is our No. 1 priority,” Carlton said in his note to parents.

“I ask that you spend some time talking with your child about school and encourage them to continue to communicate with us and with you when they see or hear something that is out of the ordinary or makes them uncomfortable,” he said.

Carlton didn’t discuss the exact nature of the threat. In a statement Wednesday he said, “This afternoon at 4 p.m., it was reported to the high school administration that there was a statement written on the bathroom stall wall that indicated the potential for a threat to the school tomorrow.

“At that time, we called the state police and at the advice of the police, for precautionary measures, we decided to evacuate the campus and cancel school for tomorrow,” Carlton said.