Port-a-potty explodes in Chicago lakefront park

Police say someone has used an explosive device to blow up a port-a-potty in a North Side Chicago lakefront park.

Chicago Police Officer John Mirabelli says no one was injured in the explosion early Friday morning and only the toilet was damaged. Officials say people in the area alerted police after hearing loud noises and car alarms.

Mirabelli says police are looking for those responsible and the department's bomb and arson unit is investigating.

The explosion came hours before thousands of people began to crowd the city's lakefront parks to see Chicago's annual July 4 fireworks display.