ARUNDEL — A 65-year-old man from Maryland was killed tonight when his Toyota Prius drifted off the Maine Turnpike and hit a tree.

Sgt. Andrew Donovan of the Maine State Police said the man and his wife, whose names were not available, were southbound around 6:30 p.m. when their car left the highway.

According to Donovan, a truck driver who was behind the couple’s car said the car’s brake lights never went on. There was also no evidence that the Toyota accelerated suddenly.

“He could have had a medical emergency or fallen asleep. We don’t know,” Donovan said.

The car slammed into a tree about 40 feet off the highway. Rescue crews from Biddeford said the man died instantly. His wife had to be extricated and was flown by helicopter to Maine Medical Center in Portland. Her condition is not known.

Donovan said police had to shut down the southbound lane of the turnpike for about 20 minutes to allow the helicopter to remove the injured woman.