Some ranges in the area do prohibit young children from handling such heavy weapons, but Last Stop allows children as young as 8 to participate. Bullets and Burgers said on its website that customers could “shoot a wide variety of fully automatic machine and belt fed guns including the AK-47, Colt M-16, MP5/40, FN FAL, Bren, M4, M249, M60, PKM and M203 Grenade Launcher.”

But Uzis are considered particularly tricky because they are light — unloaded, they weigh just under eight pounds — and powerful, making recoil tricky to handle even for adults, gun experts said. Designed for the Israeli military in the 1950s, Uzis are known for their simple design and operation, and they have been featured extensively in popular movies and video games.

“We allow children to shoot, but not a fully automatic Uzi,” said Genghis Cohen, owner of an indoor shooting range, Machine Guns Vegas. He called the shooting on Monday tragic, but added, “It was completely and utterly avoidable.”

“It was just a result of a lapse of attention,” Mr. Cohen said, “but I would never let a girl of that size shoot a fully automatic gun of that size — never.”

Mr. Cohen said that Uzis were notorious for rising as they fire, although usually to the right rather than the left. The video of the girl firing the Uzi on Monday shows the weapon rising and jerking to the left, toward Mr. Vacca.

Mr. Cohen said it was “pretty much the same situation” as in 2008 at a gun show in Westfield, Mass., when an 8-year-old Connecticut boy, Christopher K. Bizilj, accidentally shot and killed himself. In reaction, Connecticut imposed tougher gun regulations a year later, restricting access to machine guns for anyone under 16.

In the video, the girl, whose name has not been released, positioned herself before the target at an outdoor shooting range in this outpost in the Mojave Desert — one leg in front of the other, torso turned to the right, hands clutched around the grip of the Uzi, which appeared compact and light enough for her age and small build. When the girl fired her first shot, a puff of dust rose as the bullet hit the knoll behind the target. Mr. Vacca let out a celebratory “all right,” and then shifted the gun to fully automatic mode. The girl again pulled the trigger, but could not hold the gun straight as bullets came flying out at a rate of 600 rounds per minute.