Investigators say about 40 people broke into the Sears in Upper Darby last Thursday.
Upper Darby Police Superintendent Michael Chitwood says the group of young males from West Philadelphia gathered at 69th and Market and made their way to the store.
"We call them a flash mob that was out to steal and rob and pillage," said Chitwood.
Once there, the group entered the store en masse.
"Sears security saw them walk in and immediately called 911," Chitwood said.
They grabbed everything they could get their hands on. Sneakers, socks and wristwatches were among the items taken by the group.
"We got one guy with a backpack that had six pairs of sneakers in it that were stolen from Sears," said Chitwood.
Police got some of the merchandise back when they caught 16 of the suspects. All but one of them were underage, ranging in age from 11 to 16. They were all charged with retail theft.
"Where's the parents when an 11-year-old can travel three or four miles and nobody knows nothing," Chitwood said.
The mother of the 11-year-old spoke to Action News off-camera.
"It's not the parent's fault. Your children go outside to play you don't know if your child's always on 69th Street," she said.
Investigators say that adult, 19-year-old Kyree Marsh, is believed to be the ringleader. He is not only charged with retail theft but also with corrupting the morals of a minor.
No one was injured.
"Nobody tried to stop them because there were so many of them," said Chitwood. "Once again you see this 'flash mob mentality' that people think is cute or funny. It's not... it's a crime," Chitwood said.
"This could have exploded into someone getting hurt."
They also say the young people's parents should also be held accountable.
"Some parents were very supportive of the police activity," Chitwood said. "Others could have cared less."