Smoke filled three buildings on the 600 block of State Street early Saturday morning when a structural fire ignited inside a shared wall between two businesses.

At 1 a.m., State Street Brats, 603 State St., manager John Moran said he smelled wood smoke near the restaurant’s grill. However, it wasn’t until 2:30 a.m., when the building began to fill with smoke, that he called the fire department.

Public information officer Laurie Lovedale said three fire engines were called to the scene and went first into Brats to find the fire. However, after a few minutes, the firemen noticed the first floors of the Madison Optometric, 615 State St., and Tokyo Express, 617 State St., filling with smoke.

Upon realizing the fire was not in Brats, the firemen entered the two adjacent buildings and found the fire when they opened the shared wall between Madison Optometric and Tokyo Express.

Lovedale said the firemen saw no flames until they opened up the wall. They contained the fire by 3:30 a.m.

Investigators were called to the scene, but Madison fire chief Joe Aldworth said no report has been filed.

“There was very little fire damage,” Aldworth said. “However, both [Tokyo Express] and [Madison Optometric] have a lot of smoke damage.”

The exact cause of the fire and a damage estimate are not yet available because the fire is still under investigation.

The fire did not affect State Street Brats, which opened early Saturday morning for the football game, manager Matt Goetsch said. The only damage to the restaurant and bar are the holes the fire department put into the walls while trying to locate the fire, he said.

No injuries were reported, Lovedale said; however, the department did evacuate one woman from the apartment above Madison Optometric.