ORINDA -- An Oakley man who crashed a motorcycle into an embankment alongside Highway 24 on Tuesday died from his injuries, authorities said Wednesday.

An autopsy was expected to be performed Wednesday morning to determine whether a medical incident may have caused 70-year-old Fred Sprinkle to suddenly drift across three lanes of westbound traffic on his 2002 Harley-Davidson and crash near St. Stephens Drive around 1:30 p.m.

Sprinkle was driving in the second-to-left lane at approximately 65 mph when he drifted to the right shoulder and onto an embankment, California Highway Patrol Officer Kevin Bartlett said.

A female passenger was thrown from the motorcycle when it crashed but did not suffer any major injuries, Bartlett said.

Both were taken to John Muir Medical Center, and Sprinkle died later that afternoon, authorities said.

The incident marked the second fatal crash on Highway 24 in less than a week. On March 6, 17-year-old Anthony Grosso, of Danville, died after losing control of an Isuzu Impreza while going east between the Central Lafayette and Pleasant Hill Road exits. Police said Grosso was traveling at an unsafe speed.

Contact Rick Hurd at 925-945-4789 and follow him at Twitter.com/3rdERH.