The fire started in the boiler/maintenance room on top of the four-story building, but was contained to that room and did not spread to any of the apartment units, Freitag said.
Firefighters extinguished the blaze in about 20 minutes, he said.
All 24 apartments were evacuated as firefighters fought the blaze; nobody was injured in the fire, Freitag said. The apartment below the boiler room received some water damage, but no apartment sustained any smoke or fire damage.
Elise Zimmerman lives across the street from the apartments and was driving home when she noticed flames coming from the top of the building.
After she called 911, the fire "got substantially bigger. It just took off," Zimmerman said.
"Our houses are real close together here, so it is always a big concern," she said.
The 35 residents of the apartments were allowed to go back for their belongings, but nobody was permitted to stay overnight in the building. The Red Cross was helping people find accommodations.
Freitag said the fire was still being investigated and a cause had yet to be determined.