The Lindenhurst school district plans precautionary security measures two days next week at the high school after finding two threatening messages written on bathroom walls.

Although neither Suffolk County police nor a spokeswoman for the district on Friday would reveal the specific nature of the threats, the district posted on its website that extra security measures are scheduled to be in place on Dec. 10 and 11.

District spokeswoman Deirdre Gilligan said the messages threatened some type of action next Friday; they were found Tuesday and police are investigating.

A police spokeswoman said officers would be assigned to the school on Thursday and that there is no indication the threats are related to terrorism.

Christopher Gitz, the high school’s principal, said in the website posting that security measures would be put in place only “if the responsible parties are not identified by Thursday.”

Those measures include a building lockdown after 2:05 p.m. Thursday when students are dismissed and the cancellation of all school and evening activities.

On Friday, students will not be allowed into the high school until 7 a.m. and be limited to entering only through the front and rear doors.

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The police spokeswoman said there were no plans to inspect bags, but the district could request that they be searched; the district’s posting said “all bags would be subject to inspection” and that “hall passes would be restricted.”

Students also are expected to have their school identification on them at all times, the website said.

Gitz said the enhanced security measures are in compliance with district protocol and are planned “in order to safeguard all of the students and staff.”