Students evacuated Windham High School on Thursday in response to a bomb threat.

RSU 14 Superintendent Sanford Prince said the threat was discovered shortly after the school day ended at 2 p.m. Many students were gone for the day, but those who remained for sports practices and other after-school activities were immediately evacuated.

“We closed the school and got the students out of the building,” Prince said.

Prince declined to say more about the nature of the threat. State and local police responded to the school, and a Maine State Police K-9 team was also searching the building. Shortly before 4 p.m., Prince tweeted that the building was safe.

“The troopers searched the building and could not find anything suspicious,” Prince tweeted. “We will be re-opening the building this evening for activities.”

Since the Valentine’s Day school shooting in Parkland, Florida, that killed 17 students and teachers, there have been more than a dozen threats against Maine schools. More than 10 teenagers have been charged in connection with those threats.