Bodycam footage of the "chaotic" police shooting of a teenager in a California department store was released Monday, as critics claimed officers were all-too-ready to open fire.

Fourteen-year-old Valentina Orellana-Peralta was in a changing room when a stray bullet fired by a policeman came through the wall and hit her, killing her instantly.

Valentina was shopping in a Los Angeles store with her mother in the pre-Christmas rush, buying clothes for her "quinceanera", the coming-of-age ceremony celebrated by Latin Americans.

Police say they were called to the Burlington Coat Factory in North Hollywood on Thursday because of reports of a possible shooting.

CCTV Images from the scene show a clearly agitated man roaming the store with a bike lock in his hand before police arrive.

He lashes out at several people before repeatedly beating one woman about the head and body with the heavy-duty cable lock.

Police bodycam footage shows a number of officers arriving at the scene with guns drawn.

Seconds after they locate the suspect, one of them opens fire with a long barrelled gun.

He falls to the floor and is handcuffed.

More than 900 people have been shot and killed by US police in the last year, a tally by the Washington Post shows
More than 900 people have been shot and killed by US police in the last year, a tally by the Washington Post shows GETTY IMAGES NORTH AMERICA via AFP / DAVID MCNEW

A police commentary shows a freeze-frame that it says shows one of the rounds the officer fired skipping off the floor and hitting the outside wall of the changing room where Valentina was hiding with her mother.

Police Chief Michel Moore said he had ordered a full investigation of the incident.

"This chaotic incident resulting in the death of an innocent child is tragic and devastating for everyone involved," he said.

"I am profoundly sorry for the loss of this young girl's life and I know there are no words that can relieve the unimaginable pain for the family."

Hispanic civil rights group LULAC said responding officers had acted recklessly.

"It is indefensible that trained Los Angeles police officers could open fire in a crowded store at the height of Christmas shopping without first knowing for sure if the suspect was armed," said president Domingo Garcia.

The shooting is the latest in a country where law enforcement readily resorts to deadly force when confronting criminal suspects.

There is no official national record of fatal shootings by US police officers, and reporting of incidents by police departments is voluntary.

A tally by the Washington Post published Monday shows more than 900 people have been shot and killed by police in the last year.