(Reuters) - A grand jury in Columbus, Ohio, declined to charge a white police officer on Friday in the shooting death of a black 13-year-old boy who police said had pulled out what appeared to be a weapon that was later determined to be a BB gun.

The grand jury found the shooting to be justified and as a result did not consider charging the officer with a crime, Franklin County Prosecuting Attorney Ron O’Brien told Columbus television station NBC4.

Columbus police officer Bryan Mason was responding to a report of an armed robbery on Sept. 14, 2016, when he followed Tyre King, 13, into an alley, Columbus police said last year.

Before he was fatally shot, King had appeared to pull a handgun from his waistband, Columbus police said. It was later determined King had only an air pistol that fires BBs - which are small, metal pellets - not bullets.

The teenager’s death sparked protests in Columbus, the Ohio state capital, and followed a number of other police shootings of black men and boys in other parts of the United States that generated heightened public scrutiny of police use of force.

Columbus Mayor Andrew Ginther said last year the BB gun looked “almost identical” to the 9 mm Glock semi-automatic handguns carried by city police.

Ginther in a written statement on Friday called for the proceedings of the grand jury to be unsealed and for the results of the police investigation into the shooting to be made public “as soon as the law allows.”

“The death of a 13-year-old under any circumstances is tragic,” Ginther added.

Sean Walton, an attorney for Tyre King’s family, in comments to NBC4 called the investigation flawed because Columbus police took part in the probe of their own officer.

King’s death came nearly two years after the fatal shooting of 12-year-old Tamir Rice, who was black, by a white Cleveland, Ohio, police officer who was responding to reports of a suspect with a gun in a city park.

An investigation showed Rice, who died a day after the shooting, had been seen holding a replica gun that shoots plastic pellets.