Police are investigating damage caused to three Murray Bridge schools.

Last Wednesday police discovered a glass door which had allegedly been smashed at the school on Lohmann Street after police responded to an alarm activated at the school.

A pop riveter was allegedly thrown through a window causing it to smash at a school on Florence Street, last Wednesday night.

At around 6:45am last Thursday, police were called to a school on North Terrace after alarms were activated. Entry had allegedly been gained to one of the buildings and exterior glass panels were broken.