Salt Lake City firefighters responded to the fire around 12:30 a.m. Christmas morning, at 163 South and 600 East.
When they arrived they found heavy smoke and flames coming from a three-story building, and quickly got the fire under control.
Fire investigators determined the cause to be accidental. A resident told firefighters that she had discarded a cigarette into a garbage can on the back patio, which started the fire.
The apartments on the first and second floors received heavy smoke and fire damage, while the third floor unit received only smoke damage.