A motorcyclist died after he was struck by lightning while riding in rush hour traffic between Denver and Boulder, police said.

Witnesses reported seeing a flash of light shortly before the motorcyclist struck the center divider on U.S. 36 Wednesday, police spokesman Tim Read said.

Gary Missi, 46, of Longmont was pronounced dead at the scene.

A coroner's investigation was under way to determine whether the lightning bolt, the collision or something else caused his death, Read said.

The lightning blasted a 4-inch-deep hole in the highway and sent chunks of asphalt hurtling across the highway.