A 21-year-old mother in Louisiana has been accused of negligent homicide after two young children died in a house fire late Tuesday while she was away at a salon, according to police.

Ciarria Johnson allegedly left her 4-year-old daughter, Ta’shae Thompson Johnson, and 3-year-old son, Clifton Thompson Johnson, all alone at home while she went out to get her hair done. She also left two gas space heaters turned on in the wooden home in the town of Bastrop, and returned to find the house ablaze, according to an NBC News report.

A statement from the state fire marshal said that while officials are still working to piece together what happened, it is clear that Johnson “left her children unattended for hours as she was getting her hair styled.”

Authorities say the fire appeared to have started from a control valve on a gas heater that was situated in the living room, and the valve was in the “on” position. It is believed that flammable materials were too close to the heater, sparking the blaze.

Johnson claimed she had arranged for a neighbor to look after her children, but authorities said she hadn’t, and returned home only when someone contacted her about the fire, according to CNN.

Fire officials determined that two gas space heaters were running when Johnson left, and that the flammable materials near the heaters quickly caused the single-family, wood-framed house to burst into flames.

Johnson is facing two counts of negligent homicide.