WINDHAM — A Windham man was critically injured Tuesday when the 2010 Subaru Forester he was driving smashed into the back of a FairPoint Communications boom truck working on lines along Route 302.

James Callaghan, 47, was eastbound when his car veered into the truck.

Michael Pallozzi, 49, a FairPoint line worker, had just repositioned the truck at 11:30 a.m. and had stepped out of the cab onto the running board when the collision occurred, said Windham Sgt. Peter Fulton.

Pallozzi was thrown from the vehicle and received injuries that were not considered life-threatening, Fulton said.

Fulton said police are still trying to determine what caused the car to swerve suddenly. They have not been able to interview Callaghan, who was taken into surgery immediately after arriving at Maine Medical Center with critical injuries.

Flag personnel were in position at the worksite and traffic was moving slower than the 30-mph speed limit, Fulton said.

The crash near Shore Road slowed traffic for hours while the crash was investigated by Windham and state police.