Tuesday night's storm collapsed the downtown Utica building that housed the Milestone Tap, where three bodies were found early Wednesday, said coroner Jody Bernard.
She said there could be more fatalities or survivors as search and rescue efforts continued.
CBS News correspondent Cynthia Bowers reports the storm tore through the area right around dinner time Tuesday. Longtime landmarks are gone, knocked to the ground like children's blocks. 18-wheelers were tossed aside like Tonka trucks.
Early Wednesday, LaSalle County Sheriff Tom Templeton said firefighters had communicated with people in the basement of the building that held Milestone Tap and an apartment. He said those people had all been rescued and hospitalized.
Templeton said there had been no communication from anyone else in the building since. He said he didn't know the conditions of those who had been rescued.
"It's been quite a devastating night for the whole area," he said.
State officials said Tuesday night's storm was responsible for at least four deaths in and around this community of about 1,000 residents some 90 miles southwest of Chicago. A cause for the fourth death was not given.
Four other people in the area, including three children, were hospitalized with injuries, officials said. Violent storms also ripped through central Indiana, injuring at least eight people.
Authorities said from three to six people suffered minor injuries in Jamestown, northwest of Indianapolis, where about a dozen homes were damaged. One person was injured when a tractor-trailer was blown off Interstate 74 in Boone County. The storm reportedly blew as many as four semitrailers off the highway.
Rescuers in Utica, searching through the rubble of the Milestone, were hampered because the building was made of sandstone and crumbled easily.
"The structure is not stable," Bernard said.
Templeton said officials could not give an accurate account of injuries or how many homes or buildings were damaged until sometime after sunrise.
"We're holding out some hope that we'll still find some people alive," he said.
Generators roared overnight, supplying power to rescue workers toiling in the town left in the dark. Yellow police tape also cordoned off several downtown blocks where the heaviest damage occurred.
Dozens of buildings in a three- to four-block area were damaged, several collapsed in piles of brick and splintered wood, said state Trooper Tim Reppin.
"This would equate to what I saw in Plainfield 10 or 15 years ago," Reppin said, referring to the Aug. 28, 1990, tornado that killed 29 people and damaged more than 1,000 homes along a 16-mile path near Joliet.
Mervin Taylor had just finished rounding up his 22 head of cattle when he watched the huge tornado barreling toward his home take a left and head for downtown Utica.
Taylor, whose property wasn't damaged, said the tornado turned away from his property about a block away. "I didn't have time to be scared," the 72-year-old said.
State Rep. Careen Gordon, whose district includes LaSalle County, said she had been in contact with Gov. Rod Blagojevich's office and planned to ask for emergency funds Wednesday. Blagojevich spokeswoman Cheryle Jackson said the governor planned to go the region to assess the damage.
The storm collapsed a drug store roof and destroyed at least one home in the Chicago suburb of Joliet, officials there said. The storm also damaged about 60 homes and a bank in Granville.
Sam Zulbeari, who owns Ali's Pantry Family Restaurant in downtown Granville, said trees were toppled and cars and stores have broken windows but his business wasn't damaged.
"It happened so quick, we just ran to basement," Zulbeari said. "We got scared a little bit, but we're lucky we didn't get hurt. ... It's just miserable."
At least 15,000 homes were without power across three counties Tuesday night.