SIOUX FALLS, S.D. (AP) - Investigators say they're unable to pinpoint the cause of a house fire in Sioux Falls that killed three children because of the extensive damage to the home.

The Dec. 22 blaze killed 16-year-old Michael Hensley, 12-year-old Savannah Coon and 6-year-old Alivia Coon. Their mother, Rhiannon White, and her husband escaped with minor injuries by jumping from a second-floor window.

City Fire Marshall Dean Lanier says officials think the fire started in the home's living room but the cause can't be determined.

White faces drug charges for allegedly having methamphetamine and ecstasy in her body at the time of the fire. Police spokesman Sam Clemens says there was no evidence of drugs or paraphernalia inside the