A 32-year-old Sonoma man was struck and killed Thursday on Arnold Drive in El Verano by a car that drifted off the road, CHP officials said.

Just before 3 p.m., Pedro Velez Hernandez was walking north in a bicycle lane on Arnold just south of Grove Street, Sgt. Gilberto Jose said.

For unknown reasons, Thornton Bunch, 74, of Napa allowed his northbound 2004 Toyota Prius to go off the road, striking Hernandez from behind, Officer Garret Ray said.

The car crashed through a backyard fence, knocking Hernandez into the back yard.

Witnesses said the Prius appeared to be traveling at about 40 to 45 mph.

Sonoma Valley fire paramedics pronounced Hernandez dead at the scene.

Bunch was not arrested, however the circumstances of the crash were still under investigation, Ray said.

Officers closed Arnold Drive between Grove and Center streets and diverted traffic away from the area for several hours.