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CHICAGO — Authorities are searching for suspects in a shooting that critically wounded an ATF agent early Friday.

The agent was ambushed while investigating illegal guns in the Back of the Yards neighborhood about 3:15 a.m. Friday. He was shot in his face and nearly lost an eye, officials said. He remained in the hospital Friday night but is expected to recover.

Local and federal police searched homes and executed multiple search warrants Friday near the 4500 block of South Hermitage Avenue. Multiple “persons of interest” were being questioned.

A reward for any information leading to charges in the case was up to $61,000 by Friday evening.

Chicago police believe the gunman could have fired from a house. Investigators found shell casings on scene from a handgun.

“Community members can expect to see a significant presence in the area with the deployment of area gang teams, specialized gun teams and a cross jurisdictional show of force,” Chicago Police Supt. Eddie Johnson said. “My message to those responsible is simply this: We will find you.”

Johnson said police were poring over multiple surveillance videos and going door-to-door interviewing neighbors.

The ATF agent is the fourth member of law enforcement to be shot in Back of the Yards in the past year. Two officers from the Deering district were shot last May; a third officer was shot in July. All three survived.