(KRON) -- The Oakley Police Department responded Thursday morning to a fatal collision involving a pedestrian and a vehicle, authorities confirmed to KRON4. The crash occurred at 9:55 a.m. on Main Street at Ramos Ranch Road, police said. Police said a vehicle was traveling north on Main Street whe n it struck a woman who died at the scene. The incident "occurred mere feet from the home of the decedent and the family was home when the collision occurred," said Oakley PD. Authorities said the family has been notified. The driver of the involved vehicle, a 77-year-old man, was taken to a local hospital with unknown injuries. Police learned that the man "initially drove home but voluntarily returned to the scene." The vehicle is now in police custody. (KRON4) Police said an initial investigation suggests "a medical impairment" may have factored into the collision. Police are still looking to see if drugs or alcohol were involved. “The members of the Oakley Police Department are especially aware of the sensitivities of this tragic incident," said Oakley Chief Paul Beard. "The Department extends its sincerest condolences to the family.” Main Street was closed in both directions for three hours between Shady Oak Drive and Simoni Ranch Road for the investigation. It was reopened at 1:04 p.m. ...read more read less