The fire broke out at a five-story building on Washington Street around 7 p.m.
Flames could be seen shooting out of the roof of the building, which houses four floors of condos above a grocery store. Smoke and flames quickly spread, sending the fire to four alarms.
"It was only one window, and now it looks like it took over the entire building," one resident said.
No major injuries were reported, but two residents were treated at the scene for smoke inhalation and one person was taken to the hospital.
"He had some smoke inhalation, but he seems to be okay, although in shock from the trauma of getting out of the building," Mayor Dawn Zimmer said.
Several families were also displaced.
Firefighters kept the flames from jumping to neighboring buildings, but the smoke spread through downtown.
"We went into a restaurant, and the entire block just filled up with smoke," another witness said.
"I live three blocks [away]," a nearby resident said. "We smelled something in our apartment, so that's why we came out."
Flames broke out again around 6 a.m. Monday. Eyewitness News is told that wood underneath the copper roofing was still smoldering.
The fire department remains on the scene. Investigators are looking into what sparked the fire.
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