A defense attorney says a Chicago police officer made a "split second" decision when he fired on a vehicle moving away from him, wounding two teenagers inside.

Marco Proano is charged with federal civil rights violations for using unreasonable force and causing bodily injury. The 42-year-old allegedly fired multiple times into the vehicle as it backed up after being stopped for speeding.

Daniel Herbert, Proano's attorney, says the officer's state of mind on Dec. 22, 2013, boiled down to he was in a neighborhood full of guns, drugs and crime. The attorney says Proano knew something bad was happening as one teen was hanging out of a window, and "had to do something."

In her opening statement, Assistant U.S. Attorney Georgia Alexakis noted Proano pulled his trigger 16 times.

In recommending Proano's firing, the Chicago Police Department's Independent Police Review Authority noted dashcam video shows Proano firing in the direction of a person in the car he claimed to be protecting.