They came upon the scene by happenstance.
LAPD criminal gang homicide detectives pursuing an investigation, driving down 10th Avenue in South Los Angeles, saw a group of young men in an alley early Tuesday morning.
There appeared to be some sort of dispute. In his hand, one of the young men was holding what appeared to be a handgun, a .380 Automatic Colt pistol, police said.
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Only later did investigators learn it was, in fact, a realistic-looking replica — a toy — not a real gun, according to LAPD Commander Andrew Smith.
When the person holding it did not respond to commands to drop it, one officer fired his sidearm, striking a 15-year-old boy next to the suspected gunman.
The wound was not serious, and the 15-year-old was released from the hospital that same day.
"It could have been a far worse tragedy," said Smith, who sees this latest incident as emblematic of the danger created when all too realistic replicas are taken into public.
Last November, police in Cleveland shot to death a 12-year-old boy playing with a replica gun in a park.
Since a televised pursuit Monday evening in LA, when the alleged carjacker brandished what appeared to be a handgun, police have concluded that too was a replica.
Replica guns characterized as "airsoft" are found in countless toy and sporting good stores. Without using gunpowder or high pressure, they can "fire" plastic BBs at low speed, and are regarded as harmless unless a beebee happens to catch you in the eye.
To distinguish toy guns from real firearms and real BB guns, replicas must carry a bright orange ring on the tip of the barrel.
But the orange ring can be removed, covered, or repainted, and that often happens.
Teenage relatives of Denice Santos used to do that until older family members put a stop to it.
"My mother-in-law sees them, she throws them away," Santos said. "No orange tips, they go into the trash."
The replica recovered from the alley Tuesday does have the orange ring intact, police acknowledged. However, the officer may not have been able to see it at a distance
of 20 feet with the barrel pointed away from him, Smith said.
At a briefing Thursday afternoon, police displayed replicas next to the real firearms after which
they were modeled and challenged reporters to tell the difference.
Without the orange ring, it can be difficult even for firearms experts to spot the difference without closer inspection, Smith said.
A state law that will prohibit the sale of airsoft replicas without a fluorescent band and markings on the trigger guard will take effect next year.
LAPD Chief Charlie Beck is on record favoring a requirement that toy guns be entirely orange or green or some other obvious color that makes it easier to be recognized at a distance, or when the barrel is turned away.
Airsoft boxes you find marketed in the downtown LA toy district are invariably marked "ages 18 and up."
The packaging for airsofts imported from China by UKARMS contains a sheet of "operating precautions" to be followed by the purchaser.
"Never point or display this airsoft gun to law enforcement personnel as this may
be fatal," states precaution number three.