The Fox Lake police officer shot and killed while chasing three suspects Tuesday morning was a 30-year veteran of the force who went by the nickname “G.I. Joe” and was married with four children, according to police and family.

“He’s got four sons who are going to have to go on alone,” said Terry Resetar, mother-in-law of the slain officer, Charles Joseph Gliniewicz, 52.

Gliniewicz radioed shortly before 8 a.m. while on routine patrol that he was going to check on some suspicious activity, Lake County sheriff’s spokesman Chris Covelli said during a news conference.

He then radioed he was in a “foot pursuit” but communication was lost after that, Covelli said. Other officers responded and found him shot near Route 12 and Sayton Road, he said.

Gliniewicz was discovered in a marshy area, stripped of his gun and other gear, according to Lake County Undersheriff Raymond Rose. He died at the scene, the undersheriff said.

Police established a perimeter and sent helicopters into the air as they sought three suspects, described only as a black male and two white males, Rose said. Several canine units were also dispatched, as well as SWAT teams in camouflage.

With the help of U.S. marshals, teams of police from throughout the county searched surrounding woods and businesses in the area. By 4 p.m. no arrests had been made as more than 100 police officers continued the search.

Parents were asked to pick up their children at local schools.

Friends and colleagues remembered Gliniewicz as fun-loving and optimistic and dedicated to his work.

“This should never happen. Joey just loved his job,” said Thomas Poulos, a retired Waukegan police officer who said he went to high school with Gleniewicz in Antioch. They both graduated in 1981, Poulos said.

They stayed in touch and saw each other at local events and reunions, Poulos said, and it was clear that Gliniewicz — known as “Joe” or “Joey” in high school — enjoyed his job. Gliniewicz helped with the police department’s explorers program, which allows young adults to look into careers in policing.

“Loved his job, loved his kids, loved his wife, and he loved those explorers,” said Poulos, who now lives in California. “He was just a delight to be around. … Not a bad bone in his body.”

Fox Lake Mayor Donny Schmidt called Gliniewicz “a very dear friend.”

“We lost a family member,” he said at an afternoon news conference. “G.I. Joe was the father of four boys and a dedicated officer.”

Rose said police across Lake County knew Gliniewicz for his affiliation with the local police explorers program.

“He, as the leader of that, had a tremendous impact on a lot of young people in the county,” Rose said.

“Today the Fraternal Order of Police lost a fellow member and brother who died heroically serving his community,” Illinois FOP President Chris Southwood said in a statement. “Our thoughts and prayers go out to the slain officer’s family, friends and fellow police officers. He leaves a legacy of several decades of service to Fox Lake for which we are humbly grateful.”

Hours after the shooting, Nathan Muehlfelder learned that he had lost one of his regular customers at Good Family Tattoo in Lake Villa.

Muehlfelder guessed that he had done half of Gliniewicz’s body art, including tattoos of his police badges.

“He was a super nice guy. He was always loud when he was here, you could hear him a mile away,” Muehlfelder said. “He always did things for the community, especially with the police explorers. He was always a really happy guy. Never angry, always laughing.”

Residents in the area reacted with shock as armed police patrolled their neighborhoods and helicopters thumped overhead.

Jill Heyn and Brad Pekarik live in Ingleside, minutes from where the shooting occurred. They heard helicopters all morning as the search intensified and saw officers walking around Gavin Middle School down the block.

“My neighbor came out hysterical,” said Brad Pekarik, who has lived here on Stanton Bay on Fox Lake for about 16 years. “It’s not a good thing. Everybody’s a little crazy these days.”

Jill Heyn said it “feels like our paradise has been spoiled. It’s just one story after another. Blue lives matter.”

Michael Drewer, of Fox Lake, owner of the Dipstick Oil Change, now surrounded by yellow police tape, said there were a half-dozen officers blocking off roads at Sayton and Route 12 when he arrived at work in the morning.

“Then a half-hour later, [the number of police] ballooned quite a bit,” he said. “They checked our security video and then told me I wouldn’t be doing any business today.”

Covelli said the suspects should be considered dangerous and advised residents to stay indoors if possible.