CHICAGO — At least 21 people who believed they were about to purchase an item from ads on social media, were instead robbed at gunpoint in the city’s Englewood neighborhood.

Since mid-July, victims have been lured to Englewood after agreeing to buy a motorbike or an ATV, using sites such as Facebook Marketplace or Offerup. In these incidents, the victims agree to meet the supposed seller at a location — but when they show up, the person posing as a seller allegedly shows a handgun and robs the victims, before fleeing the scene.

Sixteen of the reported incidents have happened on the 6700 block of South Elizabeth Street. The latest happened just minutes apart in the 6100 block of South Campbell. Other incidents happened on the 5800 block of South Elizabeth, on the 6700 block of South Throop Street and on the 6800 block of South Ada.

Authorities are suggesting that people making purchases through online sellers to use the Chicago police station lobby to make the transaction.

According to police, there are one to four suspects involved — aged between 18 to 30-years-old. A black handgun has been used in each case.

Anyone with information is urged to call Chicago police or leave an anonymous tip at cpdtip.com.