Police in Fox Lake, Ill., are searching for three suspects after an officer was fatally shot on Tuesday while he was in pursuit of the men for suspicious activity. (Reuters)

A massive manhunt in Illinois continued Wednesday, shuttering schools in the area as authorities spent a second day searching for suspects after a police officer was shot and killed north of Chicago.

Police said that Lt. Charles Joseph Gliniewicz, an officer in Fox Lake, Ill., was shot and killed Tuesday morning after he reported that he was on foot and chasing three possible suspects.

Gliniewicz was a father of four and a decorated officer known to many as “G.I. Joe,” Fox Lake Mayor Donny Schmit said at a news conference Tuesday.

“We lost a family member,” Schmit said.

[Manhunt launched after death of an officer known as “G.I. Joe"]

The Lake County Sheriff’s Office and Illinois State Police sent deputies and troopers Wednesday to assist the Fox Lake police “in an effort to saturate the area,” Det. Christopher Covelli, a spokesman for the sheriff’s office, wrote in an email.

“When an incident like this happens, it victimizes not just the police department but the whole community, and we’re here for them,” Covelli said during a news conference.

Local agencies and federal authorities combed the Fox Lake area on Tuesday after the shooting, sending waves of officers and 48 police dogs out to search an area spanning about two square miles while helicopters skimmed overhead. The main search area was about two square miles, according to the Lake County Sheriff’s office.

The Lake County Major Crimes Task Force, which is located in the county sheriff’s office, is leading the investigation.

“We are making progress,” Cmdr. George Filenko of the task force said during a news conference Wednesday afternoon.

An autopsy on Gliniewicz was performed Tuesday night, but Filenko said he could not reveal if it provided anything useful for the investigation.

Authorities are canvassing the area, speaking to people and working through hundreds of tips from the public, Filenko said. About 100 investigators were working on the case, he added.

“I’m not going to set a time limit on this,” he said. “I have a murdered colleague, a police officer, and we’re not going to stop.”

There has been no decision on whether to offer a reward for information on the suspects, but Filenko said officials have been discussing a possible reward with federal authorities.

Gliniewicz is the 24th police officer shot and killed by a suspect this year, according to the Officer Down Memorial Page, a nonprofit organization that tracks line-of-duty fatalities.

While the number of police officers shot and killed is down from the same point last year, Gliniewicz’s death comes shortly after the high-profile killing of a Texas sheriff’s deputy who was gunned down while getting gas in suburban Houston.

[President Obama: Violence against police ‘is completely unacceptable’]

That shooting drew renewed attention to the tension law enforcement officials say they feel amid ongoing protests against how police use deadly force.

Attorney General Loretta E. Lynch spoke Wednesday at a conference in Washington about the importance of standing up for the safety of police officers, referencing the slain officers in Texas and Illinois as well as the two officers killed in Louisiana last week.

“I strongly condemn these recent and brutal police shootings in Texas and Illinois,” Lynch said, according to her prepared remarks. “We have had four more guardians slain and frankly our hearts are broken over this. I offer the families of these officers my condolences and I ask that all of us come together and keep them in our prayers.”

Lynch tied these deaths to recent shootings that have captured national attention, including the killings of journalists in Virginia, military members in Tennessee, moviegoers in Louisiana and church parishioners in South Carolina.

“We have seen violence strike at all segments of our community,” Lynch said. “It is a sad fact now that no one is safe.”

Fox Lake, a community of about 10,000 residents, is a little more than an hour north of downtown Chicago. Gliniewicz spent three decades as an officer with the Fox Lake police, according to village officials.

“The loss of Lt. Charles Joseph Gliniewicz has left a large void in our community,” Fox Lake said in a statement. “A void that can never be filled.”

A vigil honoring Gliniewicz was scheduled for Wednesday at 6 p.m. at a park overlooking a lake in the village.

Several schools in the area said they would be closed Wednesday due to the continuing search. Grant Community High School in Fox Lake, which was locked down for much of the day Tuesday, announced that it would be closing after discussions with local officials.

School officials said in a statement that “we have all decided that it is in the best interests of our students, the community, and law enforcement, to cancel school.”

The Big Hollow, Gavin and Fox Lake school districts also announced that they would be canceling classes because of the ongoing search.

“Thank you for your patience and cooperation during this very difficult time for our community,” John Ahlemeyer, superintendent of Gavin School District 37, wrote in a message to parents announcing the cancellation of school. He added: “Once again, thank you for your cooperation and patience as we pull together as a community on behalf of our children and each other.”

After Gliniewicz radioed in to say he was chasing three possible suspects shortly before 8 a.m. on Tuesday, contact with him was lost, and another officer found him with a gunshot wound, according to Chris Covelli, a Lake County Sheriff’s spokesman.

The three suspects were described only as two white men and a black man.

Schmit, the Fox Lake mayor, said that as the search unfolded, authorities would work to reassure residents that they were safe as the investigation continued.

“The coming days will be even more difficult as we remember him as a police officer, a father and a member of our community,” Schmit said.

[After Texas deputy’s death, a reminder of the increased anxiety felt by law enforcement officers amid protests]

The sheriff’s office in neighboring McHenry County said it was asked to provide officers, armored vehicles, a SWAT team and police dogs. The FBI and Bureau of Alcohol, Tobacco, Firearms and Explosives both said they were participating in the search, with the ATF deploying agents as well as dogs to help in the efforts.

The Federal Aviation Administration said it shut down the airspace over the manhunt on Tuesday afternoon at the request of the Fox Lake Police Department. This restriction bars any flight under 3,000 feet above the ground level where the search is taking place.

One of the stations on the Metra commuter rail system that was closed for much of the day Tuesday reopened for travelers on Wednesday. Metra closed the Ingleside station on the Milwaukee District North line, which runs between Fox Lake to Chicago’s Union Station, until late Tuesday night.

“The Milwaukee North Line has resumed normal operations,” Metra said in a statement Wednesday morning.

Other police departments sent the Fox Lake police condolences after the shooting:

Related:

Police officers experience fewer deaths these days — but increased tension

After arrest in ‘execution-style’ shooting of Texas deputy, a search for a motive

Nearly a quarter of the police officers shot and killed this year have been in Louisiana

This post has been updated. First published: 7:06 a.m.