MINNEAPOLIS (WCCO) – Authorities say they are still trying to determine what caused a house fire in Hibbing that killed a retired fire captain, his wife and their two grandchildren.

The fire occurred in the early-morning hours of Dec. 27 on the 200 block of 42nd Street East. When firefighters arrived, they found an 8-year-old boy alive outside the home. But two adults and two children were removed from the house, and they all died.

The adults were identified as 67-year-old Steven Gillitzer and his wife, 63-year-old Patricia Gillitzer. Authorities say they died trying to rescue their grandchildren. Steven Gillitzer got the 8-year-old boy out of the house before attempting to save the rest of the family. Two other children, 9-year-old Todd Gillitzer and 3-year-old Isaiah Adams, were taken to the hospital. Both later died.

Steven was a Hibbing firefighter for 25 years before retiring in 2000.

Authorities say the fire caused an estimated $320,000 in damage to the home, which was completely destroyed. They are still investigating what caused the fire, but say there are no indications or evidence that foul play is suspected.