Hundreds of people looted Chicago’s Magnificent Mile commercial district early Monday, smashing windows and clashing with the police for hours including at least one exchange of gunfire, the Chicago Tribune reported, citing police.

The Chicago police declined to comment when contacted by Reuters early Monday.

People darted in and out of stores along Michigan Avenue carrying shopping bags full of merchandise, the report said.

The glass pane of a Nordstrom store was shattered, according to a photograph published on the Tribune’s website.

There were no immediate reports of injuries.

The Tribune reported it was unclear what had provoked the vandalism but noted that anti-police graffiti had been spotted in at least two areas.