Fire officials said first responders were called to the crash in the 4900-block of North Route 47 around 6:45 p.m.
When they arrived, they found two teenagers had been ejected from the car in the crashed, which sent the car rolling into a house. The two teens were found nearby unconscious.
Two medical helicopters were called. One teen was flown to Javon Bea Hospital - Riverside in Rockford and the other was flown to Advocate Condell Medical Center in Libertyville. Both sustained life-threatening injuries, officials said.
The house was not damage in the crash.
The roadway remained closed Wednesday night and it was not immediately clear when it would reopen.
An investigation into the crash is ongoing by the McHenry County Sheriff's Office.