Police and prosecutors in New Jersey are asking people to please not buy a cellphone case that looks like a gun.
"It's a terrible idea, and it's very dangerous," New Jersey state police said on Facebook. "We strongly recommend that you do not use this product.
"Officers do not have the luxury of time when making split-second decisions, while interacting with the public."
A county prosecutor's office echoed the message.
Gun-shaped phone cases come in a variety of styles and can be bought through various websites, including EBay.
Through the years, many children have been shot by police who mistakenly thought the youths had lethal weapons.
In February, a Los Angeles police officer shot and wounded a 15-year-old boy who was standing next to a friend holding a replica gun.
Last year, it was announced a Northern California sheriff's deputy would not be charged after he shot a 13-year-old seven times, killing him, after mistaking the boy's realistic-looking pellet gun for an assault rifle.
One of the highest-profile cases of this kind is that of Tamir Rice, a 12-year-old boy who was holding a replica gun when a Cleveland police officer fatally shot him in November. A judge has found probable cause to bring criminal charges against that officer, who had said he had “no choice” but to open fire.