Sanders is the third officer from the Santa Fe Springs office of the highway patrol to die in the line of duty since 2004. He is the 214th death in CHP history.
The eastbound 60 Freeway was reopened about 3 p.m.
The incident remains under investigation. Authorities are not sure how fast the vehicle that struck Sanders was traveling at the time. Conditions were difficult at the time, according to officials. Investigators say it was raining and dark.
There have been no charges filed in the case.
Sanders, a Marine Corps vet who served in Iraq, is survived by his wife and three children, ages 7, 3 and 10 months. His wife is pregnant with their fourth child.
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Gov. Arnold Schwarzenegger said flags will be flown at half-staff at the state Capitol in honor of Sanders.
"Maria and I were deeply saddened to learn of the passing of Officer Joseph Sanders, who dedicated his life to ensuring public safety," Schwarzenegger said in a statement. "California is a better place because of his service and his sacrifice will not be forgotten."
Paul M. Weber, president of the Los Angeles Police Protective League, said in a statement: "We know that this news must be devastating to the family, colleagues and friends of Officer Joe Sanders, who put his life on the line so residents could be safe and secure on the highways. Our thoughts and prayers are with his CHP community, as well as his family and friends in what must be a very difficult holiday season."
A fund has been setup for the family:
Officer Sanders Donation Fund
PO Box 826
San Dimas, CA 91773