Police officers confer while searching for suspects in the shooting of police officer Lt. Charles Joseph Gliniewitz, who was killed while pursuing a group of suspicious men.

FOX LAKE, Ill. — Law enforcement officers prepared early today to resume the intensive hunt for three suspects in the fatal shooting of a popular veteran police officer in a small northern Illinois community.

Authorities from across the state and region poured into the village of Fox Lake to join the manhunt following the death Tuesday morning of Lt. Charles Joseph Gliniewicz.

Some wore tactical gear and toted high-powered rifles. Officers took up positions on rooftops and along railroad tracks, scanning the terrain with rifle scopes and binoculars. Others leaned out of helicopters with weapons at the ready. Federal agencies, SWAT teams and 48 police dogs assisted in the manhunt, Lake County Sheriff’s Office spokesman Sgt. Christopher Covelli said.

Residents of the usually sleepy village about 60 miles north of Chicago were urged to stay indoors, and schools were on lockdown. In a statement late Tuesday, Covelli urged the community to reach out with tips and leads.

Covelli said Gliniewicz radioed in Tuesday morning to tell dispatchers he was chasing three men on foot. Communication with him was lost soon after. Covelli said backup officers found him injured with a gunshot wound and that he died soon after.

An emotional Fox Lake Mayor Donny Schmit described the slain officer as a personal friend, a three-decade member of the department and a father of four sons.

“We lost a family member,” Schmit said of the 52-year-old officer known around town as “GI Joe.” “His commitment to the people of this community has been unmatched and will be dearly missed.”

The area near the Wisconsin border area is popular for boating and other outdoor pursuits because of its forest preserves and a chain of lakes that partly encircles Fox Lake. Some longtime city dwellers move to the region for what is normally a quieter lifestyle.

Authorities urged resdents to stay home while they searched for the suspects, two of them white and the other black.

Commuter train service was halted, and residents who wanted to take their dogs out to relieve themselves were told to stay inside, with the job of walking the pets handled by police officers.

Several schools were locked down Tuesday, and seven cancelled classes on Wednesday, Covelli said.

Gliniewicz’s death is the third law enforcement fatality in Illinois this year, according to the Law Enforcement Officers Memorial Fund.