Firefighters responded to the two-story building in the 500 block of S. Clarence Street just after 4 a.m., according to the Los Angeles Fire Department. Crews were able to extinguish the flames about 20 minutes after arriving.
Firefighters searched the building and found the woman, whose name has not been released, in one of the units. While smoke alarms could be heard going off in the surrounding apartments, it's unknown if the unit the woman was found in had a working smoke alarm, officials said.
The cause of the fire remains under investigation.