Just after 11:15 a.m., the Woodstock Fire/Rescue District responded to a 911 call about a man with a stab wound at the Shell gas station at 110 North Eastwood Drive.
Authorities said the man's injuries were reportedly from a knife.
A medical helicopter flew the man to Javon Bea Hospital-Riverside in Rockford in critical condition.
Police have taped off what appears to be an encampment behind the gas station.
They have not said what led to the stabbing or if there have been any arrests.