PHILADELPHIA (AP) — Groups of teenagers swarmed into stores in several areas of Philadelphia, stuffing plastic bags with merchandise and fleeing, and police arrested 15 to 20 people, authorities said.

The flash mob-style ransacking Tuesday night at stores, including Foot Locker, Lululemon and Apple in Center City, followed an earlier peaceful protest over a judge’s decision to dismiss murder and other charges against a Philadelphia police officer who shot and killed a driver, Eddie Irizarry, through a rolled-up window.

However, the ransacking was not connected to the protest, Interim Police Commissioner John Stanford said at a news conference.

“What we had tonight was a bunch of criminal opportunists take advantage of a situation and make an attempt to destroy our city,” he said.

The thefts and unrest stretched from Center City to Northeast and West Philadelphia.

Stanford said that people appeared to have organized efforts on social media. He said police are investigating “that there was possibly a caravan of a number of different vehicles that were going from location to location” and that a couple of people in that group were in custody.

Police said there was an increased presence of juveniles in the Center City business corridor shortly before 8 p.m. and that some officers stopped a group of males “dressed in black attire and wearing masks,” according to a police department news release.

At that time, reports and 911 calls were coming in about the Foot Locker store. When police arrived, they found it had been “ransacked in a coordinated attack,” the news release said. The juveniles fled and at least one adult as arrested.

By 8:12 p.m., police responded to similar calls at Lululemon, where multiple people were arrested. Shortly after that, calls directed police to the Apple Store. No arrests were made there, but the store lost phones and tablets, although many of those items have since been recovered, the news release said.

Video posted on social media showed masked people in hoodies running out of Lululemon with merchandise and police officers grabbing several and tackling them to the sidewalk.

No injuries were immediately reported, but CBS Philadelphia said a security guard was assaulted at the Foot Locker.

The thefts also occurred on the same day that Target announced it will close nine stores in four states, including one in New York City’s East Harlem neighborhood, and three in the San Francisco Bay Area, saying that theft and organized retail crime have threatened the safety of its workers and customers.