PLEASANT HILL, Iowa — Thirteen students who attend a local high school have been charged for allegedly participating in acts of vandalism at the Southeast Polk Community School District’s bus garage last week.

The Des Moines Register reported that nine 18-year-olds were cited with third-degree criminal mischief charges, which are aggravated misdemeanors punishable by up to two years in prison or up to a year in jail and a $500 to $5,000 fine. Four 17-year-olds were referred to juvenile court.

The vandalism occurred on April 21. Deputies were called to the bus barn after drivers reporting to work that morning found flat tires on buses and fish bait and used cat litter smeared inside the vehicles.

Officials said they believed that the students had gained access to the bus yard around 2 a.m. that morning through an open section of fence, which was down because of a construction project.

School was delayed for two hours while workers pumped the tires and cleaned the surfaces in 35 to 40 buses.

The cost of the damage is believed to be more than $4,000.