About 35 firefighters were called to the two-story house just before 6 a.m.
Investigators say the firefighter suffered minor burns to the legs, and was taken to a nearby hospital. Information on the firefighter's condition was not immediately available Monday.
About 60 percent of the building was damaged in the blaze.
The house is home to a family of 12, who were in Myrtle Beach when it happened.
The fire marshal's office and the ATF are investigating.