A fire at a Dexter-based Holden hog confinement facility was deemed accidental by the State Fire Marshall, who believes the blaze resulted from a loose sow.

“This was really a freak accident,” Deputy State Fire Marshall Steve Wolf said. “We know the pig had to be in the room before the fire started. The floor was clean where the pig was lying.”

Wolf said the hog escaped and may its way to a utility room, where it likely ruptured a gas line.

Mower County Chief Deputy Mark May said the total losses has also been increased to $3 million, nearly twice the preliminary estimate. The fire engulfed two buildings at 25581 640th Ave. in the early morning hours of July 2; one held pigs, the other equipment.

Wolf estimated that 400 sows, plus a unknown number of piglets, died. He said “really not much” equipment was destroyed, though noted that wage losses and other factors likely brought the value to $3 million. The deputy fire marshall spent three days on the scene with several investigators.

According to the report, farm manager Harry Wallam initially responded to the farm after receiving a call from a security alarm company about a low-level pressure alarm at the complex. Thinking it may have been a water-pressure issue, he drove there, saw the fire and called authorities.

Dexter and Brownsdale fire departments were at the scene around 4 a.m.

Holden Farms Inc., based in Northfield, is one of the largest pork producers nationwide. Holden owns Santos Group, a second large-scale pork producer operating locally.

Owner Kent Holden could not be reached for comment.