MEXICO — More than half of Mountain Valley Middle School students stayed home Wednesday, apparently after a parent posted on social media that there was an active-shooter threat.

Nick Graham’s post on the Oxford County Open Posting Facebook page Tuesday said he would not send his child to school Wednesday because there was an active shooter threat, and that the school called him and asked him “not to say anything to anyone.”

Regional School Unit 10 wrote a response on the social media page Tuesday, saying in part that the school was investigating a “less-than-credible threat.”

Superintendent Deb Alden said in an email Wednesday that the threat was made at the end of the day but it was not against students.

“Law enforcement were contacted immediately yesterday and they assessed the situation for us to determine best practice,” she said.

Alden said law enforcement was at the school Wednesday and messages were sent to all families.

Of the 400 students, 254 were absent Wednesday, Alden said.

“The main reason for a lack of details is in order to do a thorough investigation,” she said. “Student safety is our top priority. We believe MVMS is a very safe place to be,” Alden said.