Cumberland Police Chief Mike Crooke said Tuesday it could be several days before the cause of the fire is confirmed.
Eight-year-old Forrest Eppert and 9-year-old Genesis Eppert died at the condominium where they lived with their mother and two other siblings.
Crooke says their mother, Stephanie Eppert, is in critical condition with burned lungs and leg injuries suffered when she jumped from a window to escape the blaze. He says she is expected to remain in a medically induced coma for two weeks.
Police have said three of Eppert's children have autism, including the two who died.
Donations to help the family are being collected at the Cumberland police station.
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