Adrienne LeFaux and her grandmother, Alma Hart, apparently died from smoke inhalation in bedrooms at the opposite ends of the mobile home on Monday.
Two other children, a 3-year-old boy and a 6-year-old girl, escaped with minor injuries, along with their mother, who suffered moderate burns, authorities said.
Investigators said the children's father told them he looked in on the family before leaving for work and everything appeared to be fine.
The fire appears to have been accidental, but because fatalities were involved, the state fire marshal's Office is investigating, authorities said.
Donald Carter, arson superintendent with the state fire marshal's office, said the cause remained undetermined, but that investigators ``don't see anything suspicious right now.''
The fire appeared to have started in the kitchen and den area in the middle of the mobile home, he said.
