The declaration provides immediate state assistance to San Bernardino County, citing conditions of "extreme peril to the safety of persons and property" in the county due to the earthquake.
In the small town of Trona, as many as 50 structures were damaged by the quake, fire officials told the AP.
Julia Doss, who maintains the Trona Neighborhood Watch page on Facebook, said residents reported that chimneys and entire walls collapsed during the quake. She said the only food store in town has been shuttered.
In addition, San Bernardino County Supervisor Robert Lovingood said Saturday that damaged water lines prompted FEMA to deliver a tractor-trailer full of bottled water to the town, and firefighters were checking numerous reports of gas leaks.
VIDEO: Moment quake struck Ridgecrest
The town was temporarily cut off after the earthquake when officials shut down a highway connecting Trona to Ridgecrest because of rockslides and cracks in the roadway.
The hardscrabble town with 1,500 residents on the edge of a dry lake bed is considered the gateway to Death Valley.
Eugene Johnson was cleaning his home Saturday after the 7.1 magnitude earthquake brought down his brick chimney and fireplace.
The 61-year-old Trona resident told the AP that he and his wife were in bed watching TV Friday night when the quake started. They rushed into their living room to hold onto their fish tank and big-screen TV and watched the fireplace collapse.
Dishes crashed out of cabinets, boxes of macaroni fell to the floor and spilled everywhere, and the refrigerator careened halfway across the kitchen.
The Associated Press contributed to this report.