A small northern Illinois community remained on edge Wednesday morning as the tense manhunt continued for three suspects believed to have fatally shot a veteran police officer a day earlier.
Several school districts in the Fox Lake area cancelled classes and residents were warned to stay on high alert while helicopters scanned the marshlands and dense woods along the Wisconsin border.
Officers toting high-powered rifles and binoculars were joined by federal agents and more than 45 police dogs as the manhunt stretches into its second day and has broadened outside of an immediate 2-square-mile area.
"We're looking for suspicious activity, we're looking for the offenders and we want to let the Fox Lake community to know they're safe and we're keeping an eye out for them as well," Lake County Sheriff's Office spokesman Det. Christopher Covelli told reporters Wednesday morning.
Working on limited descriptions released to the public, the suspects are two white men and one black man believed to be armed with a pistol, police have said.
The search goes on as a community mourns 52-year-old Lt. Charles Joseph Gliniewicz, a married father of four young boys. The 30-year-veteran was gunned down while responding to "suspicious activity" before 8 a.m. local time Tuesday, authorities said.
After radioing for backup, officers found Gliniewicz's body in a marshy area; he was stripped of his weapon and pepper spray, Lake County Sheriff's Office spokesman Det. Christopher Covelli said Tuesday.
Hundreds of police from across the state and region poured into the village, about 60 miles north of Chicago.
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. Search efforts continued overnight and the nature of the search area now includes police fanning out into "saturation patrols," Covelli said.
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.
In and around Fox Lake, a community of 10,000, 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.
"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 Tuesday.
"Residents in here knew him as G.I. Joe, and remember him as someone deeply committed to Fox Lake," Schmit added.
A vigil is planned Wednesday night for Gliniewicz, who was set to retire from the Fox Lake Police Department last month but stayed on a while longer as a favor,NBC Chicago reported.
Gliniewicz had an enthusiasm for and dedication to law enforcement, those who knew him said. His work included guiding 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.
Congressman Robert Dold called Gliniewicz's death a "heartbreaking reminder of the sacrifices made every day by those who have dedicated their lives to protect us."
"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," Southwood said. "He leaves a legacy of several decades of service to Fox Lake for which we are humbly grateful."
This story originally appeared on NBCNews.com