WARREN – A Knox County sheriff’s deputy was seriously injured Wednesday while making a U-turn on U.S. Route 1. His cruiser was hit broadside by a trailerless tractor truck.

Deputy Justin Cook, 26, of Warren was taken by LifeFlight helicopter to Eastern Maine Medical Center in Bangor, where he was in fair condition Wednesday.

The 6:30 a.m. crash closed Route 1 for more than three hours.

Maine State Police Trooper Patrick Hood, who is investigating the accident just south of Schoolhouse Farms, said Cook suffered a collapsed lung. Stephen McCausland, spokesman for the state Department of Public Safety, said Cook suffered internal and head injuries.

The driver of the truck owned by George C. Hall & Sons of Rockland was not injured, according to police.

Steven Booker, 36, of Waldoboro was traveling north behind the cruiser.

Sheriff’s Lt. Terry Burgess said Cook had just come on duty at 6 a.m.

He was heading north on routine patrol when he apparently spotted a traffic violator “go the other way – south,” Hood said, and Cook pulled into the breakdown lane, activated his blue lights and attempted to make a U-turn. The semi braked, but was unable to avoid hitting the cruiser broadside on the driver’s side, Hood said.

The cruiser door had to be removed to free the injured deputy, who was first taken to Penobscot Bay Medical Center in Rockport by Warren Rescue, then transferred to Bangor by helicopter. Sterling Ambulance of Union and Warren Fire Department also assisted at the scene.

According to Hood, Cook was wearing a seat belt, but he did not know if the truck driver was properly restrained. No charges are expected. Both drivers were traveling alone.

Cook has been a full-time deputy for three weeks.

For the past 14 months, Cook worked part-time as a deputy while working full-time at Maine State Prison as a guard. He had been employed by the prison since January 2002, according to sheriff’s Chief Deputy Todd Butler.