MUSTANG, Okla. —  Mustang school officials sent notes home with students from Mustang Middle School (search) on Monday that threats had been made against certain students.

"This morning at 10:30 a.m., the administrator at Mustang Middle School discovered a written threat that stated: 'On Thursday, March 31st, all Christians and preps will be shot,"' said Superintendent Karl Springer.

Mustang police spokesman Capt. Willard James said the school district reported the threat to the police department immediately.

"The threat was written on a boys bathroom stall, and as of this afternoon it had been written on three bathroom stall walls," James said.

"There are security measures that are being put in place right now. We are going to assign an officer to the middle school until this issue is resolved."

James said the middle school currently does not use metal detectors.

"We consider all threats made to our schools are serious," James said.

Approximately 890 students attend the school.