As a small northern Illinois community mourned a popular veteran police officer who was fatally shot while on duty, authorities scoured the area overnight in search of three men wanted in his slaying.

Helicopters were to aid about 100 officers early Wednesday as the manhunt in and around the village of Fox Lake for the suspects in the fatal shooting of Lt. Charles Joseph Gliniewicz stretched toward a second day, a sheriff’s office spokesman said.

Authorities from across the state and region poured into the village about 60 miles north of Chicago after the shooting Tuesday morning, some wearing tactical gear and toting high-powered rifles.

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Federal agencies, SWAT teams and 48 police dogs assisted in the search for the suspects, Lake County Sheriff’s Office spokesman Sgt. Christopher Covelli told The Associated Press.

Gliniewicz, 52, a 30-year veteran and father of four young boys, was found fatally shot after reporting that he was chasing on foot three male suspects engaged in suspicious activity shortly before 8 a.m.

His body was found in a marshy area, authorities said. The officer’s weapon and pepper spray were missing.

The initial search focused on an area of 2 square miles and lasted for 14 hours, the Lake County Sheriff’s Office said late Tuesday. The perimeter was released at around 10 p.m. and the scene was turned over to a task force, the sheriff’s office said. Patrols were continuing around Fox Lake.

“Today, not only did Fox Lake lose a family member — I lost a really dear friend,” Fox Lake Mayor Donny Schmit said at a news conference. “Residents in here knew him as G.I. Joe, and remember him as someone deeply committed to Fox Lake,” Schmit said.

Image: Fox Lake Lieutenant Charles Joseph Gliniewicz

Image: Fox Lake Lieutenant Charles Joseph Gliniewicz

Illinois State Police said several teams, including SWAT and air operations, were helping in the manhunt Tuesday night. The federal Bureau of Alcohol, Tobacco, Firearms and Explosives and the FBI were also assisting.

The suspects are described as two white men and one black man. Hundreds of police officers were involved in the manhunt Tuesday, NBC Chicago reported. The men are believed to be armed with a pistol, Lake County sheriff’s Chief Doug Larsson told the station.

In and around Fox Lake, a community of 10,000 about 60 miles north of Chicago, residents were asked to stay indoors. Police have even taken people’s dogs outside to relieve themselves rather than let residents do it themselves, The Associated Press reported.

Image: Police officers search an area for suspects involved in shooting an officer

Image: Police officers search an area for suspects involved in shooting an officer

Police officers and SWAT teams in camouflage scoured the heavily wooded area as helicopters conducted a search from the sky.

Gliniewicz was remembered Tuesday for his enthusiasm and dedication to law enforcement, including working with children as part of a local Police Explorers unit.

“He would always try to help everybody,” youth member Thomas Ashbacher told NBC Chicago. “He would give his shirt off his back if he could.”

Illinois state Rep. Barbara Wheeler asked the community for prayers. “Fox Lake lost a true hero today,” she said.

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“Today the Fraternal Order of Police lost a fellow member and brother who died heroically serving his community,” Illinois Fraternal Order of Police President Chris Southwood said in a statement to NBC Chicago.

“Our thoughts and prayers go out to the slain officer’s family, friends and fellow police officers,” the statement said. “He leaves a legacy of several decades of service to Fox Lake for which we are humbly grateful.”