The National Rifle Association has provoked controversy after apparently releasing a shooting video game aimed at children as young as four.
Critics say the sale of the iPhone and iPad app, NRA: Practice Range, weeks after the Sandy Hook school massacre is insensitive.
The game features a series of shooting ranges and a choice of handguns, rifles and shotguns, including the assault rifle used in the Newtown killings.
Players have one minute to pick off as many targets - some coffin-shaped - as possible, then post their scores on a public leaderboard.
The game has been released three weeks after the NRA's executive vice president Wayne LaPierre blamed "vicious, violent, video games" and the wider entertainment industry for gun rampages.
Billed as "the NRA's new mobile nerve centre", the app also allows access to information about gun safety, legislation and news from the four million member US gun lobby.
According to the description on iTunes, the game is intended to instill "safe and responsible ownership through fun challenges and realistic simulations."
Because it contains "no objectionable material" according to iTunes' rating system, it is advertised as suitable for children as young as four.
Connecticut Democrat Senator Christopher Murphy has written an angry letter to Mr LaPierre and Aplple CEO, criticising the release.
He wrote: "The NRA seems intent on continuing to insult the families of the victims of Sandy Hook.
"How could they think it was a good idea to use the one month anniversary of the tragedy at Sandy Hook to release a game that teaches four-year-olds to shoot assault weapons?
"No matter what outrageous new tool they use, the NRA cannot make a straight-faced case that sport shooters need military-style weapons to enjoy their hobby."
One angry visitor to the games App Store review page wrote: "Is this some kind of sick joke? The NRA complains about violent video games and then releases one a week later.
"Sure you're not shooting at humans... does it really matter?"
But in a reflection of how guns divide Americans, others gave the app five-star reviews.
"Freaking awesome," wrote one satisfied customer. "Better hurry and download this before they take it away from us," added another.
The game's release coincided with this week's SHOT show, an annual trade show for the shooting, hunting and firearms industry, organised in Las Vegas by the National Shooting Sports Foundation, a gun industry trade group.
The foundation happens to be based in Newtown, Connecticut, where Adam Lanza, 20, murdered 20 children and six teachers at Sandy Hook Elementary School on December 14.
Lanza, who had earlier shot and killed his mother, owner of the Bushmaster assault rifle used to kill the children, also took his own life in one of the most worst mass shootings in US history.
Some commentators have suggested the game may be a hoax aimed at embarrassing the NRA.
Former New York Times editor and columnist Bill Keller said web experts have suggested some of the NRA branding used in the app indicates it could be fake.
The pro-gun organisation has declined requests to comment on the release.
President Obama will outline his plans to curb gun violence in the US on Wednesday.