CHICAGO (CBS)– The Chicago Police Department is warning Near North area residents of a string of recent robberies.

In each incident the offenders approached the victim from behind, forcibly grabbing cell phones and purses from their hands, according to police.

In one incident, police said the offender threatened the victim with a blue semi-automatic handgun.

Offenders were seen fleeing the scene in a silver Ford Escape. Police said the offenders may also be driving a blue Audi Q5 four-door vehicle.

The offenders are thought to be between 20 and 22 years of age. Police said there is believed to be one to four male offenders and one female offender.

Anyone with information is asked to contact officials at 312-747-8380.