Investigators are looking into what caused a fire at a popular Rock County bar Wednesday night.

The fire at the Night Owl Food and Spirits in Evansville started around 10:15 Wednesday night on the building's back porch before spreading to the roof and fully engulfing the building, fire officials said.

Officials said when crews arrived, the back porch was fully engulfed. Evansville police officers and bystanders tried to put the fire out with fire extinguishers, but they were not successful.

A fire department spokesperson said there is extensive water damage and part of the roof is missing.

Evansville fire chief Terry Wendt said firefighters were on the scene for nearly six hours fighting the blaze.

Families in the two buildings to the west of the bar were evacuated while the fire was burning. There were people in the restaurant at the time of the fire, but no one was hurt.

The building is more than 100 years old. Since some of the bricks fell, the structure might not be able to be saved.

"It was one of the original downtown buildings, probably back in the 1800s, the later 1800s," Wendt said.

Because of the falling debris, East Main Street was closed from Madison Street East to Railroad Street, and Maple Street was closed from Main Street to just north of the Evansville Veterinary Clinic overnight. Pedestrian access to the area was also be limited.

The bar was truly a community place, Evansville resident Arlene Larson said.

"We go to the Night Owl often, and I’m really sorry that this happened to it. It was a great restaurant. It was one of the few restaurants in town, and a lot of people went here. You would go here to see games and just hang out with your neighbors," Larson said.

"A lot of the people in this town are going to miss this business because they had great food here and stuff. So, it’s just a shame to see it go," Wendt said.

Evansville police and fire personnel are working with the Wisconsin State Fire Marshal to investigate the fire.

Officials ask anyone with information on the incident to call the Evansville Police Department at 608-882-2292.