A 53-year-old man was killed Tuesday morning in a motorcycle crash in the Beltsville area, authorities said.

The incident occurred about 6:15 am on Powder Mill Road just west of Route 197, said Sgt. David Schlosser, a U.S. Park Police spokesman. He said Robert Mack, a Beltsville resident, was killed when he laid down his motorcycle and collided with a guardrail.

It remains unclear why Mack laid down the bike, Schlosser said. The motorcycle appears to be the only vehicle involved in the crash, he said.