The Sherburne County Sheriff’s Office is investigating a suspicious house fire in Big Lake that killed two young children and critically injured their father early Friday morning.

The agency said in a news release that investigators suspect the father, 36, intentionally set the fire, which killed his 1- and 2-year-old children and injured two other children, ages 7 and 9, who also lived in the home.

The Star Tribune is not identifying the family members in keeping with a general policy of not naming criminal suspects who have not been charged.

According to Sherburne County Sheriff Joel Brott, Big Lake police and firefighters responded to the fire at 5:37 a.m. They broke down the door and rescued five people from the home, including four children.

All of the occupants were taken to local hospitals. The father and the 7- and 9-year-olds were hospitalized; the father remains under guard.

The State fire marshal is investigating and will make a final determination about the cause of the fire.