Napa police said Towe's car struck a tree in the parking lot of the Home Depot at 225 Soscol Ave. around 12:20 p.m. Saturday.
Witnesses broke a window of the car to remove Towe, who was unconscious, and began CPR, Napa police Sgt. Paul Paniagua said. The Napa Fire Department responded and continued CPR.
Sheriff's Capt. Tracey Stuart said Towe was pronounced dead at 12:55 p.m. Saturday at Queen of the Valley Medical Center in Napa.
Towe, a Napa resident, did not die as a result of the crash, Stuart said. An autopsy will help determine Towe's cause of death, but one hasn't yet been scheduled.
Paniagua said Towe may have suffered a medical problem just before the crash, and that it does not appear alcohol was involved.
It's unknown if Towe suffered a medical event that caused the collision but alcohol was not involved in the crash, Paniagua said.
Anyone who witnessed the crash is asked to call Napa police at (707) 257-9223.