The officer was identified as Officer William Jones, who was assigned to the LAPD's North Hollywood station, according to a department statement.
The Los Angeles Police Department released no other immediate information.
The girl was with her mother in a dressing room, trying on Christmas dresses, two days before Christmas, when she was struck by a police bullet that passed through a wall on the second floor of the Burlington store at 12121 Victory Blvd.
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Valentina Orellana Peralta died in the arms of her mother, who said she and her daughter sat down and hugged when they heard the commotion in the store. The force of the gunshot that struck the teen threw them both to the ground, the girl's mother said.
Los Angeles police on Monday released body-camera footage and other details of the shooting when officers responded to reports of a man assaulting people, and possibly firing shots, inside the Burlington store.
The narrated video released by the LAPD includes footage showing the assault suspect viciously attacking a woman on the second floor of the Burlington store, repeatedly beating her with a steel or metal cable bike lock, leaving her bloodied on the floor as officers arrived.
Body-camera video captures the sound of police gunfire quickly ringing out as officers spot the suspect -- with the cable lock in his hand. More than a half-dozen officers descend on the suspect after the shots are heard, and the injured suspect is taken into custody.
The assault suspect, 24-year-old Daniel Elena Lopez, was later pronounced dead at the scene.
While the video shows the suspect with the cable lock in his right hand, there is no indication he is armed with a gun, and it is unclear if he advanced on any officers before the shots rang out. Police have said no gun was found at the scene.
The video released by the LAPD Monday includes audio from a series of 911 calls. In one call, a store employee tells a dispatcher a suspect is in the store attacking people with a bike lock. In another, a woman reports the sound of shots being fired in the store, saying there's "a guy with a gun.''
Another caller reports that her mother was hiding inside the store because of a man making threats. She added, "I don't know if he has a gun, I don't know what he has, but they're hiding.''
A GoFundMe page established to benefit the teen's family had raised nearly $30,000 by midday Tuesday.
MORE | LAPD releases bodycam video of fatal shooting at Burlington store