Police arrested a man after he walked into Alton Middle School's Olin building during cheerleading practice and told everyone to get out.
Mark Casey is charged with possession of cocaine and for restraining the cheerleading coach.
According to Alton Middle School's principal, the cheerleaders were wrapping up practice around 5:20 p.m. on Monday, when the man walked into the practice room from the outside.
"He walked in and told everybody to get out," said principal David Schwartz.
The cheerleading coach was in a storage room, putting away the stereo used for practice, at the time. Schwartz said that when she tried to step out of the storage room, the suspect pulled the door shut from the outside in an attempt to keep the coach in the room. The coach called for the students to get out of the practice area, and she ran out of a second exit, located in the storage room.
A custodian dialed 911 and school officials say police, nearby, were arrived within a minute.
"When police found him, he was face first in the prone position with one arm under him, one behind his back, just laying there," said Schwartz.
Witnesses also reported that the suspect kept saying, "this is my house."
Schwartz said no one at the school recognized the suspect.
He got in through an exterior door that automatically locks, but the door had to be pulled shut in order to close properly. Students were walking out the practice area and it's believed the exterior door did not latch.
The school has since had the door repaired.
"It's kind of a wake-up call that we pay attention to these things more closely," said Schwartz.
He says that school security guards patrol the campus during the day and that all exterior doors remain locked. Teachers and staff enter through main entrances, equipped with keypads. Visitors have to be buzzed in, at the main office.