COLUMBIA FALLS, Mont. -

In Columbia Falls, a controlled burn that got out of hand Tuesday evening left almost 40 acres of wildland scorched. Officials tell NBC Montana a man is dead after allegedly trying to fight it.

Flathead County Undersheriff Dave Leib told us a 67 year old man appeared to have set a controlled burn, but the fire got away from him. Investigators discovered his body near the head of the fire Wednesday morning. Leib says the man likely over-exerted himself and died of a heart attack. 

The Office of Emergency Services spent most of Wednesday mopping up the fire, and look to complete clean up by Thursday.

"There's so much heavy fuel down there. Trees that are 40 inches in diameter that are burning," said Fire Service Area Manager Lincoln Chute. "When you have that much fuel and heat it, it can last for a long time. And there's big slash piles. We have to get those torn apart with an excavator so that we can put them out otherwise they'll smolder half the summer. It can haunt us later in the summer when it's fire season."

The name of the 67 year old is being withheld until his family is told about the death. Investigators are counting on an autopsy to pinpoint why he died.