"She wasn't breathing when we brought her out of the house," Shirley said.
The child's mother was in cardiac arrest and was revived by emergency responders in the front yard, Shirley said.
She was found in the living room and her son was found on the floor in another room of the one-story house, according to Shirley. The boy was pronounced dead by county Medical Examiner Carole Spessert, Shirley said. An autopsy will be conducted in Morgantown, W.Va., to determine cause of death, said Greg Hoover, Martinsburg Fire Department's chief fire investigator.
The cause of the blaze, reported at 2:30 p.m., remains under investigation, Hoover said.
Heavy fire damage in one room, and smoke and heat damage throughout the structure were not readily apparent from outside the home. Only one side window was broken out and pieces of charred furniture and insulation removed from inside were lying in a small gravel driveway just below a smoke-darkened opening.
The fire also extended into the attic, Hoover said.
When Shirley arrived, light smoke was coming out of the eaves and the fire inside was quickly extinguished, he said.
The Berkeley County Ambulance Authority was needed to assist with emergency response because the city's EMS crews were already handling other calls, Shirley said. The Berkeley County Office of Homeland Security and Emergency Management also responded, Hoover said.
Shirley said the Martinsburg Police Department was "a great asset" in helping with the emergency. The police department also provided security outside the home.
Hoover said the fire department cleared the scene at about 8:30 p.m.
A neighbor said the woman recently moved into the home, which Hoover said she did not own. The owner's name was not released.