Early Wednesday a male driver lost control of his truck while traveling on Highway 116 west of Guerneville, and drove down an embankment into a tree, according to the CHP.
The truck's driver was rushed to Santa Rosa Memorial Hospital and was determined to have minor injuries, the CHP said.
The crash was reported at 5:54 a.m. near Cnopius Road.
Emergency vehicles responding to the crash briefly blocked the major west county route and traffic was reduced to one lane until 7:40 a.m.
Russian River firefighters found the truck about 30 feet down the embankment with the driver still inside. They helped him out and into an ambulance.
What caused the man to crash remained under investigation Wednesday morning. CHP officials said officers are looking into whether the man, who was reportedly 70 years old, could have suffered a medical emergency prior to losing control of his truck.