Crews were called around 11:10 Friday night to the Waterfront Apartments near 2nd and Market streets.
Arriving firefighters were met with dozens of people exiting the building while smoke poured from the second floor.
"We ended up running outside because the smoke was billowing thorugh our hallway," said Matt Lafferty, resident.
The blaze was brought under control within a half hour and crews remained on the scene for an hour cleaning up.
No injuries were reported. The Red Cross is assisting at least two people affected by the fire.
The resident who lives in the unit where the fire started was not home at the time.
No word what sparked the blaze.