Kentucky State Police confirm a house fire in Harlan County, Kentucky, has now claimed a third life.

Three-year-old twins Alex and Olivia Howard – who would have turned four in June – died in a Monday-morning blaze at a home along State Highway 522 in the Totz community.

Their mother, 42-year-old Allyson Howard, succumbed to her injuries in a hospital in Augusta, Georgia, Wednesday. Family members say Howard had severe burns over 84 percent of her body. Her husband, Dennis Howard, is still hospitalized in critical condition.

The cause of the fire remains under investigation.