Police believe the car may be a newer, dark-colored four-door Toyota Camry with tinted windows.
Police said early Wednesday morning, the officer had just finished his shift when he was shot in the back of the head near police headquarters on the 200-block of East 37th Street. His female passenger was not injured while he was taken to the hospital for emergency surgery.
WATCH: Supt. Johnson discusses shooting of off-duty CPD officer
Chicago Police Superintendent Eddie Johnson said the 25-year-old officer has been on the force just two years and worked in the 6th District, alongside the superintendent's son. Johnson grew emotional speaking about the shooting Wednesday, saying he worked alongside the injured officer's father.
"This officer has seen his share of gun violence while working in the 6th District," Johnson said. "Illegal guns have had a significant impact on a lot of neighborhoods in this city. Today, the same violence has left one of our own clinging to life."
The officer remains hospitalized at the University of Chicago Medical Center in critical but stable condition, police said Thursday morning.
CASE UPDATE: We are seeking a newer 4 door Toyota Camry, dark in color, with tinted windows. Detectives have isolated the suspect vehicle on multiple cameras and are working to trace its path of travel with traffic and city POD cameras. pic.twitter.com/jsuxTJoduT— Anthony Guglielmi (@AJGuglielmi) June 27, 2019
Chicago gun violence on Johnson's mind again Thursday morning as he discussed city crime with U.S. attorneys in Washington D.C.
"I vow to continue putting every effort into stemming the tide on gun violence in Chicago," Johnson said.
Mayor Lori Lightfoot addressed the shooting Thursday morning.
"I absolutely understand some of the feat that a number of people have about reporting what they are seeing, but that's why it's critically important that we keep building avenues of trust," Mayor Lightfoot said.
The Chicago Police Memorial Foundation a reward for information leading to the arrest of the young officer's attackers. The award was originally $10,000, but doubled Thursday morning after the foundation said it received, "many donations to help up the reward," police told ABC7.
The suspect's car was last seen going southbound on Michigan Avenue from 37th Street.
Anyone with information is asked to contact Area Central detectives at (312) 747-8380.