Harvey police officers were on the scene moments after responding to the initial call of a robbery at a t-shirt shop in a strip mall.
One officer was shot and immediately transported to Ingalls Hospital after responding to a call about a robbery at a business near Wood Street.
The officer sustained non-life threatening injuries and is now in stable condition.
The suspect took off on foot after firing shots from a handgun.
The Harvey Police Department, along with the Illinois State Police, Cook County Sheriffs and numerous local law enforcement agencies are searching for a male suspect, according to the mayor's office in Harvey.
Investigators say the suspect was wearing black clothing and had on a black face mask inside the store.
Harvey police are joined by state, county and officers from nearby towns in the search for the suspect.
Police say they are unsure whether he was hit in the exchange of gunfire, but are using all available resources including dogs, to find the suspect, who is considered armed and dangerous.
There were reports the officer was shot in the arm, but no other information was provided.