The blaze quickly grew to 1,200 acres (485 hectares) after starting on Saturday afternoon, the California Department of Forestry and Fire Protection said yesterday.
The person who died has not been identified, and authorities are still trying to determine how the person died.
Evacuation advisories were issued for residents of Jamesburg and the nearby community of Cachagua, Cal Fire said.
One of those fires, which killed at least three people, was 53 percent contained. Another 6,400 homes remain under threat.
The other fire destroyed 535 homes and killed at least two people. That blaze was 70 per cent contained yesterday but continued to threaten thousands of structures. All evacuation orders there were lifted, however.
A weekend of heat descended on the wildfires after several favourable days, raising fears that major gains could be undone. That makes it essential that the smoldering remains of the two giant blazes be dealt with as quickly and thoroughly as possible, Scott Mclean, a battalion chief with the California Department of Forestry and Fire Protection, said.