Image copyright Genesse County Sherrif's Office Image caption One of 20 rocks found on the highway after the incident

Five teenagers have been charged with second-degree murder in Michigan after a rock thrown from a highway overpass killed a man in a passing van.

The 6lb (2.7kg) stone smashed through the vehicle's windshield and struck Ken White, 32, US media report.

The suspects, aged 15 to 17, later drove to a McDonald's restaurant to eat, a sheriff said.

They were each charged with one count of second-degree murder, as well as conspiracy to commit murder.

"I don't believe that this was a deliberate attempt to take somebody's life," Genesee County prosecutor David Leyton was quoted as saying by the Chicago Tribune.

"It was a wilful and wanton act that resulted in somebody's death."

At least 20 rocks were found on Interstate 75, including one weighing almost 20lb, and at least four vehicles were damaged.