CHICAGO (CBS) — Several people have been robbed on CTA trains and platforms in the Loop and South Loop in the past two weeks.

Police said CTA passengers were targeted in five robberies since July 18.

Up to three robbers would threaten or punch their victims before stealing their belongings, such as cell phones, from their hands or pockets.

The holdups happened during the afternoon and evening hours on CTA trains and platforms:

• around 5:20 p.m. on July 28, at the Roosevelt station on the Red, Orange and Green lines;

• around 8:05 p.m. on July 23, at the Roosevelt station;

• around 4:25 p.m. on July 24, at the Washington station on the Blue Line;

• around 8:10 p.m. on July 26, at the Harrison station on the Red Line;

• around 3:20 p.m. on July 27, at the Jackson station on the Blue Line.

Police did not have a detailed description of the robbers.

Detectives also are investigating another incident on an Orange Line train last week.

Surveillance images show a man standing near the exit on the train and snatching a woman’s property from her hands as he walks off the train at the Roosevelt stop around 3:30 p.m. on July 24.

Investigators released surveillance images of the thief. The man, who appears to be 17 to 21 years old, was wearing a grey Adidas T-shirt, dark grey sweatpants, and white gym shoes.

If you recognize the man, police said you should call Area Central detectives at (312)-747-8380.