Sheriff's Sgt. Tim Curran said Deputy Duke Lewis was in Sacramento's Mercy San Juan Trauma Center with a left shoulder wound.
Curran said police made three arrests, but were searching for a fourth suspect on Sacramento's northeast side. One suspect surrendered only after police fired at least one shot and tossed a flash-bang grenade into a backyard shed where he was hiding.
Curran said Lewis unknowingly approached the masked suspects after the Wells Fargo bank was robbed in Rocklin, 20 miles northeast of Sacramento. He said the deputy didn't know about the robbery or that the suspects had eluded Rocklin police in a high-speed chase on Interstate 80.