A 56-year-old Ashburn man died Tuesday after his vehicle ran off the Fairfax County Parkway and struck a sound barrier in the Franklin Farms area around 1 p.m., police said.

Robert Bittner, of the 21300 block of Sorrel Grove Court, was pulled from his car by passing motorists and his vehicle caught on fire soon after, Fairfax County police said. The accident occurred near Franklin Farms Road, according to police.

Police are still investigating why Bittner’s car left the roadway. Alcohol and speed are not considered factors in the crash.