CHICAGO (CBS)– John P. Rivera, 23, has been identified as the off-duty Chicago police officer who was fatally shot in River North Saturday morning, according to the Cook County Medical Examiner’s Office.

Police confirm Rivera and three other individuals were sitting in a parked car when two men approached their vehicle near Clark and Huron Street.

One man showed a handgun and started shooting. The offenders fled the scene.

Rivera was pronounced dead at Northwestern Memorial Hospital just before 4 a.m.

Another individual in the car was also shot and remains in surgery at Northwestern Hospital. A second off-duty officer was also in the car and was not injured.

First Deputy Supt. Anthony Riccio said Rivera was working 3rd watch in the 6th District and had completed a shift around 9 or 10 p.m.

Riccio said Rivera had been with the department for just under two years. Officials said one person of interest is being questioned.

Police said there were many surveillance cameras in the area where the shooting took place. Detectives are looking through footage to see if they can get video of the shooter, who remains on the run.