Jack Lee Breiner also exchanged fire with Modoc County Sheriff Mike Poindexter before being shot himself and arrested, Undersheriff William "Tex" Dowdy said.
Hopkins was responding to a disturbance call at a property about 8 miles south of Alturas at about 10:30 a.m. when he confronted Breiner, who drove off after the shooting, Dowdy said.
Dowdy said Poindexter caught up with Breiner and exchanged gunfire before hitting Breiner with a shot. Breiner was taken to a Redding hospital for treatment.
Breiner is a registered sex offender and was convicted of lewd and lascivious acts wtih a child, according to California's Megan's Law database.