HIALEAH, Fla. -- Four children were killed in an early morning house fire Sunday. Their mother and another child survived the fire that police say has a questionable origin.

Three girls ages 6 months, 6 years and 12 years old, and a 17-year-old boy died in the fire at 531 E. 41st Street in Hialeah. A 13-year-old boy and the children's mother, Maria Auguste, 43, survived the fire.

The fire broke out shortly after midnight and gutted the one-story pink stucco house, melting the decorative metalwork that covered the doors and windows. Officials said the bars on the windows and door, common in the neighborhood, may have contributed to the deaths by making it hard to escape the burning home.

Neighbors said Auguste ran back into home to get the children and was severely burned. She is in critical but stable condition with burns over 30 percent of her body at Jackson Memorial Hospital.

The 13-year-old boy is recuperating at Miami Children's Hospital and is reportedly doing well.

Two other women who live in separate quarters on another side of the house were not hurt, police said.

Records indicated that the children were taken away from Auguste under a court order in July. Officials reportedly found the children hiding in a shed when they went to remove them from the home. They were taken into the Department of Family and Children's Custody, but were returned to Auguste. Records did not indicate exactly when or why the children were returned.

The fire reportedly started in the living room near the front door. The cause of the fire is still under investigation. Investigators said they have not ruled out arson as a cause.