Investigators said the fire department responded to a fire at the 4200 block of S. Kirkwood around 11 p.m. Tuesday and found an adult woman with burn injuries.
She told firefighters that she was sleeping when someone set her on fire.
A witness dragged her away and extinguished the flames.
She was taken to Memorial Hermann Medical Center and is expected to survive.
Police do not know what was used to light the woman on fire. They are working to obtain surveillance video from the parking lot cameras.