About 700 firefighters, including members of the town's volunteer department, were battling the fire they thought was extinguished but flared Monday, the Los Angeles Times reported Tuesday.
A U.S. Forest Services representative said about 21 percent of the fire was contained and one outbuilding had burned.
Air tankers have been called in for water drops and to disperse flame retardant around the community of 10,500.
The mood in Sierra Madre was more like "a heightened state of awareness," resident Jim Carter told the Times.
"This is just part of the cycle," said Carter's 52-year-old wife, Mary, who said she lived in Sierra Madre her entire life. "This is the fourth big fire I've been through."