Police are investigating an “unfortunate accident” in which a movable wall collapsed and killed a 2-year-old girl at a Chicago-area mall, The Chicago Tribune reports. According to Orland Park Police, Alexa Martinez was playing inside a shoe store with her relatives on Tuesday afternoon when one of them hit a movable wall—causing it to fall and trap the toddler underneath it. Cmdr. Eric Rossi said the wall, which was about 8 feet tall and weighed between 75 to 100 pounds, knocked Martinez unconscious. She was transported to a local hospital and briefly regained her pulse before being pronounced dead. The store closed on Tuesday after the incident and remained shuttered on Wednesday. Rossi said the Orland Park building department was notified of the incident, though a department official reportedly did not respond to a request for comment.