The medical examiner has confirmed a brother and sister who died in a house fire Tuesday morning in Keokuk died of smoke inhalation.

Another sibling and the parents of the children were standing outside their burning home when fire fighters arrived. The two adults suffered serious burns and were taken to a hospital in Keokuk, then flown to the burn unit at University of Iowa Hospitals.

The cause of the fire is still under investigation. Fire fighters found two-year-old Elizabeth White and four-year-old Dylan White dead inside the home. The other child was not injured in the blaze. Thirty-four-year-old Matthew White and 25-year-old Joyce Boley suffered extensive burns, according to authorities.

Neighbors called 911 shortly before five o’clock Tuesday morning to report the blaze.