Nevaeh Pratt was pronounced dead at the scene, and her father, Kenneth Pratt, 38, suffered third-degree burns over 50 percent of his body, authorities said.
He was taken to the North Carolina Jaycee Burn Center at UNC Hospitals in Chapel Hill, where he was listed in critical condition Monday.
"I tried to go over there and kick the door in, but something was blocking the door," Montez Avant said.
Investigators said the fire started in the kitchen, but they hadn't pinpointed a cause by Monday afternoon.
Nevaeh Pratt's aunt, Bianca Edwards, said she thinks a faulty stove started the fire.
Relatives called the girl a "miracle child," Edwards said, because she had been born prematurely and wasn't expected to live. Nevaeh is "heaven" spelled backwards, she said.
"It was a good chance she wasn't going to make it, but she did," Edwards said. "She was happy. She was a happy little girl."
"She was just so sweet, and she was a good child," neighbor Cristal Rodriguez said.
Neither Edwards, who lives in the adjoining unit in the duplex, nor Nevaeh's mother was home at the time of the fire.