The officers returned fire but it is not known if they hit anyone, according to a police statement. Extra security is being provided for the officers and their families.
The motive remains unclear, but police spokesman Anthony Guglielmi told the Associated Press that they believe the officers were targeted.
"We will get them", Johnson said, vowing to bring the shooters to justice.
Investigators on Wednesday reviewed video from surveillance cameras at two businesses near the shooting scene to try to determine whether the shooting had been captured, employees said.
Chicago Police said the officers were shot by some inside of a vehicle. "Now it's the guns, then more recently the rifles have been introduced into our neighborhoods".
The officers were sitting in an unmarked auto in the 4300 block of South Ashland Avenue around 9pm (2pm Wednesday NZT), following up an earlier investigation, when they saw someone in a silver van shooting at another vehicle, according to preliminary information from police. Eddie Johnson said Tuesday night outside Stroger Hospital. Witnesses told CBS2 Chicago they heard several rounds fired, and a rifle reportedly was recovered as police searched for suspects. A year-long federal investigation into the Chicago police force has identified a pattern of abuse and excessive force, especially in predominantly black and Hispanic neighborhoods, Attorney General Loretta Lynch said Friday.
Marchers use Trump's 100th day to protest climate policies
Both the march and rally were peaceful and took place without incident. "Now when you go to Lake Erie it's really handsome ". Ken Hunter, 78, traveled from Charlestown, W.Va. for Saturday morning's march. "I thought it would be easier".
Two of the gangs - La Raza near 47th and Loomis streets and the Almighty Saints near 45th and Wood streets - have been fighting for decades.
Minutes later, a procession of police vehicles raced north. Graham said the officers have been on the force for some time, but did not disclose their ages or genders.
As of about 10:30 p.m. Mayor Rahm Emanuel could be seen briefly outside Stroger Hospital.
Syrian activists say a large explosion in a northern town along the border with Turkey has killed at least five people and wounded many others.
"We will be keeping our prayers with them as we go through this ordeal", he said.
The officers were in an unmarked tactical van conducting an investigation into a previous gang-related shooting.