RICHLAND TWP, Allegheny County — A Butler County woman was killed Sunday afternoon when the three-wheeled motorcycle she was driving slammed into the back of a pickup truck on Route 8, authorities said.

Pamela A. McCarthy, 68, of Middlesex Township was pronounced dead at the scene of the crash near Tom Henry Chevrolet, according to the Allegheny County medical examiner’s office. An autopsy was planned today.

Northern Regional Police said McCarthy was traveling south on Route 8 about 2:45 p.m. when her Harley-Davidson cycle struck the back of a Ford F-150 pickup that was stopped to make a left turn into the Chevy dealership.

Gregory Samios, 37, of Valencia, the truck driver, had his turn signal on, police said. He was not hurt.

The wreck happened in the left southbound lane on the four-lane highway.

Investigators noted that it did not appear that McCarthy, who was wearing a helmet, applied her brakes before the collision.

“There were no skid marks,” Chief Bob Amann of the Northern Regional Department said this morning.

Police said neither road nor weather conditions was a factor in the crash.

“The accident is still under investigation as to the cause,” Amann said.

The accident closed the road for nearly three hours.