According to Camden police, it happened around 6:00 Sunday morning on John Street, near the intersection of Pearl Street.
Authorities say 26-year-old William Tassi was driving on John Street when his vehicle crossed the street, went off the road and hit a tree before it came to rest in the roadway.
A nearby neighbor called to report the accident after hearing the crash, police say.
Camden firefighters say they had to extricate Tassi from the vehicle.
He was treated at Pen Bay Medical Center before being transported via LifeFlight helicopter to Central Maine Medical Center in Lewiston with serious injuries.
Police say speed may have been a factor in the crash.
The accident remains under investigation.