MADISON, Wis. -

A west side apartment complex sustained $15,000 worth of damage caused by a fire in the basement utility room early Sunday morning, officials said.

Crews responded to a smoke detector system going off at 6701 and 6715 Park Edge Drive around 2:05 a.m. Sunday, according to a release. The complex houses two side-by-side buildings with four residences in each.

Firefighters said they noticed a slight smoke haze throughout the building where eight units shared a basement.

Crews forced a door in the basement area open and extinguished the fire within 20 minutes, according to the release.

Officials said a fire door to the utility room helped confine the fire and minimize the spread of smoke throughout the apartment complex.

All residents evacuated the building safely and were able to return to their apartments, according to the release.

The cause of the fire is under investigation.