The single-vehicle crash happened around 1:45 a.m. Sunday, Dec. 8, on Hell Hollow Road in Griswold, according to Connecticut State Police.
The 2008 Honda Civic was traveling east when the driver veered off the road and struck the rocks and tree. The driver, a 38-year-old from Voluntown, escaped the wreck with minor injuries. However, paramedics rushed his passenger to William W. Backus Hospital in Norwich.
Doctors later transferred him to Hartford Hospital because of the severity of his injuries, authorities said.
The crash remains under investigation.
Connecticut State Police are asking anyone who witnessed the crash or has information to contact Trooper Timothy Wengloski at 860-848-6500, ext. 5.
Click here to follow Daily Voice Windsor and receive free news updates.