The fire burned late Tuesday night at a duplex in Conyers, east of Atlanta.
Another child, who is 6, was thrown by his mother from a second-floor window, Glenn Allen, a spokesman for Georgia's fire commissioner, told The Associated Press. The child injured his shoulder in the fall but survived.
"It saved his life," Allen said of the mother's actions.
The mother was taken to Grady Memorial Hospital in Atlanta with second- and third-degree burns, Allen said.
Seven people were in the home: a grandmother, the mother and five children, Allen said. The children who died range in age from the infant to 7 years old, Conyers police Major Mike Waters told reporters.
They were in one unit of a two-story duplex in the town about 25 miles east of Atlanta. The other unit of the duplex was vacant, Allen said.
Officers arrived on the scene quickly after the fire was reported around 11 p.m. and tried unsuccessfully to put it out with handheld fire extinguishers, Conyers Police Chief Gene Wilson told WXIA-TV.
There was no indication what caused the blaze, Allen said before daybreak Wednesday. He said fire investigators planned to enter the structure at first light and try to find a cause.