CHICAGO (WLS) -- Police warned drivers to stay alert in downtown Chicago after reports of people being robbed as they sit in traffic.A motorist named T.J. shared exclusive dashcam video with ABC7 Eyewitness News to make sure other drivers saw what happened to him.He was stopped at a light near North Michigan Avenue and East Wacker Drive earlier this week. Instead of crossing the street, a teen knocked on his driver's side window. That's when a second person opened the car door on his passenger side and quickly grabbed T.J.'s phone."I was really in shock, like, it happened. Like, 'Oh my God, I can't believe it happened to me,'" T.J. said.Police have been warning drivers about this type of crime since the summer. They said in many of these crimes, the suspects pretend to be handing out flyers in an attempt to distract the driver.