Aquinas High School students in La Crosse had some company during classes on Friday.
The school requested a police presence throughout the day following a graffiti incident in March.
An investigation into the incident determined there was no threat warranting the school be closed. School officials requested the presence as a precautionary measure.
Aquinas issued this statement to parents.
"In this type of situation, we wanted to exercise an abundance of caution in keeping students and staff safe. We have several more safety measures on the horizon to increase the safety of our most precious resource, your children, and our students."
School president Ted Knutson said, "In the times we live in, schools should take everything seriously and do whatever needed to address it."