The blaze broke out at about 8:45 a.m. Wednesday in a converted garage behind another home on the 12900 block of Sunburst Street.
Officials are investigating whether the home was up to code and whether there were any electrical issues, because firefighters say the home caught fire very quickly and was fully engulfed in flames when they arrived on scene.
After crews quickly knocked down the fire, they found the body of a woman inside the home. A man escaped the flames, and witnesses say he appeared to be in OK condition.
"I saw him actually coming out of the house with burns on his face," described area resident Jeff Diaz, who added that another neighbor told him he saw a female getting covered in a white sheet.
"We're pretty sure it was his girlfriend," Diaz added.
Some neighbors say there was frequent drug activity in the home.
Los Angeles Police Department officers, L.A. City Fire crews and arson investigators were all on scene.