GULF COUNTY, Fla. (WMBB) — A Marianna man was killed and his passenger was seriously injured in a single-vehicle crash, according to the Florida Highway Patrol.

The wreck happened at about 1:30 p.m. Tuesday on County Road 386 just south of Highway 20. Troopers wrote that the driver, a 50-year-old man from Marianna, was headed north on 386 when for an unknown reason he traveled off the roadway. Troopers added that the driver attempted to steer his truck back onto the roadway but it overturned.

The driver was thrown from the vehicle. His passenger, a 42-year-old man from Campbellton, was seriously injured in the crash.

The crash remains under investigation.