OKLAHOMA CITY - Firefighters responded to a duplex fire, Friday morning near Northwest 23rd Street and North May Avenue. 

One man was inside the home during the time of the fire, but was able to safely evacuate, fire officials said. 

The fire was contained to the living room of the home and caused extensive damage, firefighters said. 

Authorities believe the fire was caused by a space heater. 

There were no working smoke alarms inside the home. 

This is a developing story.