According to police, two off-duty police officers, and another man and woman were sitting in their vehicle after leaving a nightclub.
Two men approached their vehicle, displayed a handgun and then started firing multiple shots into the vehicle before running away.
The 23-year-old off-duty officer was shot in the chest, arm and mouth, police said. He was pronounced dead at the hospital.
The other victim, also 23, suffered wounds to his chest and arm, and was also taken to the hospital in critical condition.
Chicago Police Department held a press conference releasing the most up-to-date information about the incident.
Off-duty officer killed press conference raw
Police said the shooter is still at large and believe this was a random attack. Police have another person of interest in custody. They said there was no confrontation and no known motive at this time.
Officials said the officer killed had just gotten off his shift before going out to the club. They said he has been on the force for about two years.
The identity of the CPD officer is expected to be released soon.