It has been a tense day for parents of students at Harrow Public School.

There was an increased police presence at the school Thursday, following alleged threats of gun violence written on a wall in a boys locker room.

Essex OPP were notified of the threat Wednesday evening.

Police say they have identified the origin of the threat, and there was never any risk to students, staff or visitors.

The situation is now being handled by the school internally. But many parents decided to keep their children home from school.

The Greater Essex County District School Board tells CTV Windsor nearly half of the 400 students at Harrow Public were absent Thursday.

Kelly Ellenberger decided to keep two of her children home from school.

“The reality is these are our kids lives so I'm not going to take the gamble" says Ellenberger.

Parents say they weren't notified of the situation until after 10 p.m. Wednesday with an automated phone call saying a message had been written on a wall and that there would be an increased police presence at the school Thursday.

Ellenberger is critical of the school board for the late notification. But school officials insist the proper protocol was followed.

Many parents say they will also keep their children home from school on Friday.