"I would argue our police officers were compelled to act when they saw that 13-year-old with a gun in his hand," Baltimore Police Commissioner Kevin Davis told reporters.
Two plainclothes detectives, one male and one female, were returning from a strategy session on how to deal with a recent spate of gun violence when they spotted the teen walking down the street, Davis said.
They identified themselves and ordered him to drop the gun, but the boy ran for about 150 yards with the officers in pursuit, Davis said.
A witness interviewed by both CNN affiliate WBAL-TV
and by the police said the boy turned back toward the officers with the gun in his hands before he was shot.
"I heard him yell, 'It's not real,' like twice, and that quick, the male officer shot him twice in the leg," said the man, whom the station identified only as Bryan.
One of the two officers, a 12-year-veteran named Thomas Smith, shot the teenager twice, once in the leg and once in the shoulder, according to Davis.
The teen is expected to recover from his injuries, police said.
What police at first thought could have been a gun turned out to be a Daisy Powerline 340 .177-caliber BB gun. The weapon is meant to be used for target shooting,
according to Davis.
Davis called the weapon "a dead-on ringer for a Beretta 92FS semiautomatic pistol."
Davis said he did not know why the teenager had the BB gun or why he ran. He said officers had interviewed the teen's mother and that she knew he had left the house with the gun.
He defended the officers' actions, saying officers couldn't have known the gun was a replica.
"They did what the community expects them to do," he said.
Police can't just watch someone "walk down the street in broad daylight anywhere in Baltimore with what looks like to be a semiautomatic pistol in his hand," Davis said. "We can't call 911, we are 911."
Officers, he said, had no idea what the teen's intentions were.
The shooting came on the first anniversary of violent protests
over the death of Freddie Gray
while in Baltimore police custody.
It also occurred two days after the city of Cleveland agreed to pay $6 million
to the family of 12-year-old Tamir Rice, who died in 2014 after police shot him while he was in possession of a replica handgun.
While police spokesman Detective Donny Moses said Baltimore was quiet overnight and into Thursday, reaction was mixed on social media.
"We have more questions than answers today," Baltimore civil rights activist DeRay Mckesson said on Twitter
. "Why did the Baltimore officers approach the 13-year-old child? Why did they shoot him?"
One Twitter user told Baltimore police, "Awesome job! I hope you arrest his mother for negligence or contributing to delinquency. She's unfit."
But on Facebook, Darren Willis said in a reply to the police update on the incident
that "cop kissing jerks" praising the department had missed the point.
"How was he to even know they were cops? He was 13 and ran away from grown-assed men who were strangers and armed. Details matter. I know, blame the target and the mom. It's easy for racists and idiots."