 -- A manhunt is underway in Chicago after two on-duty police officers were shot and wounded by an at-large gunman who fired "indiscriminately" in what is thought to be a targeted attack, the Chicago Police Department said.

The officers, both male, were conducting an investigation on the city's South Side when "one, possibly two vehicles, pulled alongside them and started firing indiscriminately at the officers," Chicago Police Superintendent Eddie Johnson said during a press conference early Wednesday morning.

One officer was shot in the arm and hip and the other in the back, Johnson said. Both are expected to make a complete recovery and both have since been released from the hospital, police said.

"Right now, there's an extensive manhunt underway for the individuals responsible and we will get them," he added.

Police spokesman Anthony Guglielmi told The Associated Press, "We believe that the officers were definitely targeted."

The officers were dressed in plain clothes and wore vests with police badges on them. They were conducting a follow-up investigation to a previous incident when they were hit, according to authorities.

"It's just another example of how dangerous this job is," said Johnson. "And I think people take it for granted that when police officers come to work every day, they put their lives on the line every single day they get in their car."

The police department is questioning three people of interest and two guns have been recovered, police said. It's believed the officers were shot by high-powered weapon, according to police.

Chicago Mayor Rahm Emanuel tweeted, "Tonight was a frightening reminder of the dangers our dedicated officers face. Thank you @Chicago_Police for putting service above self."

Johnson noted that the area where the shooting took place had experienced gun violence in the past.

"We have to do something about the gun violence in this city," he said. "If they will fire at police officers like that, then they have no type of thought process in terms of firing at other citizens in this great city."

Witnesses reported hearing as many as 30 shots of gunfire; some said it sounded like an assault rifle firing.

One witness, who declined to give her name, told ABC affiliate WLS in Chicago that she was waiting at a nearby bus stop when the incident occurred.

"They weren't messing around," she said. "I've seen shootings but I've never seen anything like that."

The Associated Press contributed to this report.