The crash happened around 2:25 p.m. near the intersection of Route 176 and Dean Street in McHenry County, the Woodstock Fire/Rescue District said.
A motorcycle and a minivan were involved in the crash, fire officials said. A man and a woman who were riding the motorcycle were unconscious on the scene when first responders arrived, and a bystander was performing CPR on one of them.
The woman was airlifted to a hospital by helicopter and the man was transported to a hospital in an ambulance, and both had serious life-threatening injuries, officials said.
A man who was driving the minivan was also injured and taken to a hospital with non-life-threatening injuries, officials said.
The crash comes after a woman was killed in another nearby crash on Dean Street earlier this month.
The Lakewood Police Department and McHenry County Sheriff's Office continue to investigate the crash.
No further information was immediately available.