Chicago police have warned residents about several groups of up to eight girls which are assaulting and robbing female shoppers who are walking city’s famed Loop shopping district.

Chicago police reported that three African American girls, two 15-year-olds and one 13-year-old, have been arrested after being seen on surveillance video beating a female walking alone in the city’s Loop. The victim, one of several, was also robbed of her belongings, according to DNAInfo Chicago.

Officials said the gangs of teen girls would sneak up behind a lone shopper, grab at her purse and/or bags, and push the women down and punch and kick her before running off with the goods.

The roving gangs of between five and eight girls would essentially swarm around the victim and attack on all fronts. The pedestrians were often struck in the head immediately, police said.

“One 15-year-old was charged with three felony counts of robbery; one 15-year-old was charged with one felony count of robbery; and the 13-year-old was charged with one misdemeanor count of battery,” Chicago’s ABC affiliate reported.

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