MONTVILLE – David L. Stevens, 48, of Swanville was killed and three of his passengers were injured when the vehicle in which they were riding slammed into a maple tree off Route 220 on Monday.

Rear seat passenger Shirley Dunham, 13, of Brooks suffered head and neck injuries and was taken by LifeFlight helicopter to Eastern Maine Medical Center in Bangor, where she was listed in serious condition, according to investigating officer Thomas Ballard of the Maine State Police.

The other rear seat passenger, Tiffany Bucklin, 13, of Belfast, Stevens’ stepdaughter, suffered a broken leg. Stevens’ front seat passenger, Dawn Meservie, 15, of Liberty, suffered facial cuts and bruises. Stevens was engaged to marry Merservie’s mother.

Neither Stevens nor his passengers were wearing seat belts.

Stevens was traveling south on the rural Waldo County highway and was on a straightaway when for some reason the vehicle crossed into the opposite lane, went down into the ditch on the shoulder and smashed into the tree, according to police.

The impact turned the car sideways and it came to rest perpendicular to the road. There were no skid marks on the road surface, leading authorities to believe that Stevens fell asleep at the wheel.

“One of the girls noticed that he looked tired and had turned to say something to him when the car suddenly drifted across the road and hit the tree,” said Ballard.

Stevens had just picked the girls up at Mount View High School in Thorndike and was on his way to Liberty to drop them off when he crashed.

The accident happened opposite the Thornley residence at approximately 11 a.m. Stevens’ 1991 Chevrolet Lumina had just passed White’s Corner and was on the straightaway when it left the road. Fire and rescue personnel from Montville, Liberty, Searsmont and Belfast were dispatched to the scene. The passengers were taken by ambulance to Waldo County General Hospital for treatment. Dunham was stabilized at the hospital before being airlifted to Bangor.

The accident halted traffic along the two-lane highway for nearly an hour. Department of Transportation road crews that were in the area stationed their trucks a few hundred feet from either end of the accident to prevent vehicles from passing through.

State police Sgt. Peter Stewart, Trooper Patrick Hood and Waldo County Deputy Sheriff Merl Reed assisted at the scene.