MADISON, Wis. -- State investigators said Tuesday they can't determine what caused a fatal fire at a southwestern Wisconsin bar.

The Silver Dollar Saloon in Blanchardville caught fire early Monday morning. Four people -- Daniel Hardekopf and Jelayne L. Hughes, the bar's owners, as well as Cody D. Olson and Brian K. Monte -- died in the blaze.

State Fire Marshal Tina Virgil said her investigators have concluded their work Tuesday. They said a coroner has determined all four victims died of smoke inhalation.

Virgil's office said the fire began in a void space between the building's second and third floors. Investigators could not determine a cause, but there was no evidence that the fire was set or of any foul play.

The scene was released by law enforcement to the insurance company as of 1:30 p.m. Tuesday. Authorities said the structure is a total loss.

The loss of four local residents and a mainstay downtown business has stunned many members of the small community. Family and friends are still processing what happened and grieving a loss just before the holidays.

Margaret Lehr, Monte's mother, said she is heartbroken at the news.

"(It's) devastating," she said. "It's hard."

Bartender Lindsey Gant said that she knew the four victims.

"They were all very strong-willed, very wonderful people. And they always made you feel welcome every time you walked in the door," she said.

Roy Ruegsegger, who lived next door to Olson, said that the news is a shock.

"It's such a tragedy to lose four people and people you know," he said. "You think that life goes on and you have to learn to live with it, but it's hard to learn to live with it."

A professional structural engineer brought in to evaluate the structure has determined, for safety reasons, that the building should come down.

Hardekops and Hughes lived in the building while a bartender said that the group liked to watch movies after closing up the bar and that might be why they were there. Monte apparently lived across the street, WISC-TV reported.

Blanchardville lies 30 miles southwest of Madison.

Stay tuned to WISC-TV and Channel 3000 for continuing coverage.