By Michael Fleeman

LOS ANGELES (Reuters) - Los Angeles police were investigating on Thursday the shooting of a 15-year-old boy who was shot and wounded by a police officer who saw a person next to the teenager pointing what turned out to be a replica gun, police said.

The Los Angeles police department said officers from a gang homicide unit had been conducting a follow-up investigation on Tuesday when they encountered several people, including one carrying what appeared to be a gun.

"Officers saw that individual pointing the firearm at another individual," a police statement said. "Officers ordered him to drop the weapon multiple times. The individual ignored the officer's commands and an officer-involved shooting occurred."

The 15-year-old, who was not identified, was shot once in the upper back, while the person who had been holding the replica was not injured. The wounded boy was treated at a local hospital and released to his mother after the incident in a south Los Angeles alley, police said. No arrests have been made.

The incident was under investigation by the Force Investigation Division and also will be reviewed by the police chief, Police Commission and the Los Angeles County District Attorney's Office.

"Further investigation revealed that the weapon being used was a replica firearm, which has been booked as evidence,” the police statement said.

At least one officer has been taken out of the field, placed on desk duty and ordered to undergo an assessment by a psychologist, which is routine in officer-involved shootings.

This latest shooting follows protests nationwide over killings of unarmed black men by police, although the ethnic background of those involved in the Los Angeles incident were not immediately made public.

On Wednesday, a rookie New York City police officer was charged with second-degree manslaughter and five other offenses for the fatal shooting of an unarmed man in the dark stairwell of a housing project last November.

Last November, a 12-year-old boy was fatally shot by a Cleveland police officer responding to a call about a suspect brandishing a gun in a park. It turned out that sixth-grader Tamir Rice was carrying a toy gun.

(Editing by Cynthia Johnston and Sandra Maler)