WALES, Maine — Oak Hill High School was evacuated and locked down because of a bomb threat Tuesday morning, according to authorities.

The Androscoggin County Sheriff’s Department said a high school teacher noticed the word “bomb” written on a wall inside the school and reported it to the Sheriff’s Department at 9:01 a.m.

Students were placed on school buses after being evacuated.

Deputies went to the school along with personnel from the Wales and Sabattus fire departments. Maine State Police brought a bomb-sniffing dog to the school.

After the school was cleared by the dog at 10:15 a.m., the students were brought back into the school and a general assembly was conducted. The Oak Hill faculty and staff sent out messages to parents to advise them of the incident, which is still under investigation.

Police learned that some students had seen the writing on the wall Monday, April 1, and dismissed it as an April Fool’s Day joke.

Anyone who has any information about the writing and who may have done it is asked to contact James Jacques or Lt. Glenn Holt at the Androscoggin County Sheriff’s Department. The number is 753-2599 and tips can be made anonymously.