According to the Los Angeles County Fire Department, flames were reported shortly after 10:30 a.m. at a two-story structure in the 1100 block of East Franklin Avenue.
More than 20 firefighters extinguished the blaze, which left one of the girls dead at the scene, the agency said in a statement. Paramedics rushed the other girl to a medical center along with a third victim, a woman who sustained minor injuries.
The victims ages were not immediately disclosed.
"It appears the two minor females became trapped in their bedroom with access to the front door blocked by fire," the Fire Department said.
Their escape through a bedroom window was "hampered by furniture" and an air-conditioning unit that was mounted outside the window, the news release said.
The cause of the fire is unknown.