Officials said Brandon Willoughby, 11, and his half-brother William Stubbs, 7, died in the fire.
The mother of both boys and the father of William Stubbs were in the home at the time of the fire. They were checked for smoke inhalation, and investigators want to explore possible fire causes with the mother.
Officials have determined that neither Christmas decorations nor a space heater were responsible.
The fire began in the center of the mobile home; the two boys were in a back bedroom.
The rental mobile home had no smoke detectors.
The single-wide mobile home was situated at Farr Mobile Home Park, off US 1, between Vass and Southern Pines.