After graffiti referencing guns was found in a middle school, the entire Gull Lakes Community School District is closed Tuesday.
Officials in the district – which is near Kalamazoo – are still trying to identify who's responsible for the graffiti.
The graffiti was found in a boy's bathroom and on a desk at a middle school in the district, which is near Kalamazoo.
In a message on the district's website, the superintendent said students have also made several "inappropriate" comments about possible violence against other students.
Schools are scheduled to reopen Wednesday with extra police on campus.
The added security will last until the end of school year.