This story is being updated as new details emerge.

DOWNEY — A young girl who was critically injured in a Downey apartment fire that killed her mother died at a hospital, fire officials said Wednesday, and a woman believed to be the girl's grandmother remained in critical condition with burn injuries.

The fire was reported at 10:47 p.m. Tuesday in the 9400 block of Tweedy Lane, according to the Downey Fire Department.

"Arriving units reported heavy smoke and fire from a garage ...," according to the fire department. "Crews were notified of a possibility of three trapped occupants. Once on scene crews found one patient in front of the building suffering from significant burn injuries. That patient was treated and transported to a local trauma hospital.

"During the fire attack, crews were able to locate two additional occupants," the fire department reported. "Both victims were treated on scene. One victim, a minor, was transported to (a hospital), where the victim was later pronounced deceased. The other victim was pronounced deceased on scene."

Downey Fire Department Battalion Chief Jorge Villanueva told reporters at the scene that the two people inside the building were a mother and daughter who were found inside an upstairs bathroom, both in full cardiac arrest.

The mother died at the scene, and the daughter, reported to be 12 years old, died at County-USC Medical Center, according to the fire department. Their names were withheld, pending notification of relatives.

The woman who was found outside the building is the girl's grandmother, according to reports from the scene, and she remained hospitalized Wednesday.

"It hits us all pretty hard," Villanueva told reporters, noting the proximity of the fire just before Christmas.

Fire officials said the blaze appeared to have started in the garage then spread to the actual apartment. The cause remains under investigation. Crews extinguished the flames in 25 minutes, and prevented them from spreading to adjacent units.

According to reports from the scene, the apartment did not have a Christmas tree inside.

Mother, daughter killed in Downey fire