A California Department of Fish and Wildlife officer encountered Dorner on California 38 while driving in the opposite direction, the department said. The wildlife officer recognized the wanted ex-officer and began to follow.
A shootout ensued and Dorner escaped on foot, the department said. The officer called for backup, which included officers from Fish and Wildlife, the San Bernardino County Sheriff's Department and other agencies.
The wildlife officer was not injured but his vehicle was riddled with bullet holes, officials said. The officer was one of six the state agency lent to the search effort in recent days.
Dorner was believed to be holed up in a nearby cabin, which was engulfed in flames by late Tuesday afternoon. Television footage showed thick black smoke and orange flames pouring out of the building.