UPDATE 3:44 p.m.: Audio has been released of an Illinois officer discovering Charles Gliniewicz's body in a Fox Lake marsh Tuesday morning, according to Fox News.

"Send everybody you possibly can," said an unidentified officer. "Officer is down." 

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An Illinois police officer was found dead after he reported following three suspects engaging in strange activity, prompting a massive manhunt for the suspected killers, deemed armed and dangerous, according to Fox News.

Lt. Charles Gliniewicz, a 30-year-old veteran police officer for Fox Lake, was fatally shot Tuesday morning after calling in to dispatchers that he was following three suspects on foot, two white males and one black male.

It's suspected that Gliniewicz was stripped of his weapon after the incident.

Lake County and Illinois police have been sent to help comb the Fox Lake area, with helicopter assistance, in search of the suspected killers, along with 48 police dogs, U.S. Marshalls, the FBI and various other federal agents, according to the Washington Post.

Commander George Filenko of the Lake County Major Crimes Task Force said that there were about 100 investigators on the case sifting through hundreds of leads and talking to individuals.

Several school districts have closed in response to the shooting, according to CNN.

The officer's murder comes just weeks after the execution-style slaying of Darren Goforth, a Texas deputy who was supposedly shot and killed at a gas station simply for wearing a police uniform.

U.S. Attorney General Loretta E. Lynch made a response to the recent police killings in a conference on Wednesday.

"I strongly condemn these recent and brutal police shootings in Texas and Illinois," she said. "I offer the families of these officers my condolences and I ask that all of us come together and keep them in our prayers."