It’s happening in Philadelphia, Chicago and Washington, D.C.: mobs of teens traveling together and committing crimes, some violent in nature. Officials in those cities want it to end immediately.

In what are being described as flash mobs, groups of teens gather, walk into establishments, steal merchandise and walk right back out. With strength in numbers, the act overwhelms store officials.

In Chicago, teens hit the high-end fashion stores on Michigan Avenue known as the Magnificent Mile. According to the Chicago Sun-Times, law enforcement officials and merchants say that although they haven’t noticed a rise in shoplifting, there is a surge in flash mob activity.

“Is there an epidemic? No,” John C. Chikow, president of the Greater North Michigan Avenue Association told the Sun-Times. “Is there an issue? Absolutely.”

Police officials in the Washington, D.C. area may say it is an epidemic. A flash mob assault on a convenience store occurred in Northeast Washington during the early morning hours of Aug. 18. This marked the third time it has happened there in two weeks, according to Fox 5 News. That incident comes in the wake of a series of similar incidents in the trendy DuPont Circle neighborhood of Northwest D.C.

Earlier this month, in Germantown, Md., a suburb of Washington, D.C., teens hit a 7-Eleven in a mass theft that caught the Montgomery County Police off guard.

“We’ve not seen anything like this before,” Capt. Paul Starks told the D.C. Examiner.

The problem appears to be much worse in Philadelphia, though. The mob attacks there have become violent with an 11, 16, and 17-year-old being charged in a July 29 assault. The issue there has gone beyond elementary law enforcement and has the mayor of the city looking at serious social issues in the Black community as the root of the problem.

“That’s part of the problem in our community,” Philadelphia Mayor Michael Nutter told the congregation of Mount Carmel Baptist Church according to the Associated Press. “Let me speak plainer: That’s part of the problem in the Black community. … We have too many men making too many babies they don’t want to take care of and then we end up dealing with your children.”