A massive manhunt for three suspects in the fatal shooting of an Illinois police officer was widened Wednesday. Meanwhile, hundreds of people gathered at a Fox Lake park for a vigil in memory of slain officer Charles Joseph Gliniewicz, who was shot Tuesday. 

An intensive 14-hour "grid search" of homes and marshland in the village of Fox Lake was underway with no concrete clue into the whereabouts of the suspects. Authorities also looked into surveillance videos and interviewed residents near the area where the 50-year-old was found dead.

The initial 2-square-mile perimeter established Tuesday was extended on the second-day manhunt. At least 100 investigators were on ground to locate the three suspects, whose descriptions were not available to police. Gliniewicz had reportedly told dispatchers that he was in pursuit of three suspicious men -- two white, one black -- moments before he was shot.

"That was the only description provided," Lake County Major Crimes Task Force Cmdr. George Filenko, the lead investigator on the case, told the Associated Press (AP). "So of course we're getting the public calling in every time they see that match of three individuals or even two individuals. We've closed out those leads completely as being unsubstantiated."

Gliniewicz, a 30-year police veteran who was on the brink of retirement, was shot Tuesday morning while pursuing the men he spotted on his way to work. Gliniewicz had reportedly told dispatchers that the suspects ran into a swampy area and requested a second unit to chase them down.

"My world got a little bit smaller with his passing, and he will truly be missed by all of us," the officer's widow, Melanie Gliniewicz, said during her the vigil, adding that he was her "best friend, my hero, the love of my life for the last 26 and half years."