Just after 8:00 Wednesday night, Belfast Police, Waldo County Sheriff's Deputies, and Maine State Police were called to the on ramp of Route 1 by the bridge.
"She was ping-ponging off the guardrails from one side to the other all the way down until she impacted the truck that was stopping at the stop sign to get onto Route 1," Sergeant John Gibbs, of the Belfast Police Department, says.
The female driver of the red Hyundai has unknown injuries as of Wednesday night and was LifeFlighted to Eastern Maine Medical Center.
The operator of the truck suffered minor injuries.
Officials are investigating the cause of the crash to determine if any other factors contributed to the driver's loss of consciousness, though they say alcohol does not appear to be a factor.