HIBBING, Minn. (AP) — Authorities say a second child has died after a house fire at the home of a retired firefighter in Hibbing, bringing the death toll to four.

The Hibbing Fire Department says the fire broke out early Tuesday at the home of retired fire Capt. Steve Gillitzer. Authorities say the 67-year-old Gillitzer and his wife, 63-year-old Pat Gillitzer, died in the fire. Two of the couple's grandsons, 9-year-old Todd Gillitzer Jr. and 3-year-old Isaiah Anteus Adams, died at hospitals.

Another grandson, 8-year-old Jonathan Gillitzer, had minor injuries and was found outside the house. The fire department says the boy's grandfather woke him up and threw him out the front door to safety before trying to rescue other family members.

Firefighters battled the blaze in subzero temperatures. The cause remains under investigation.