The gun range instructor was showing the girl how to hold and fire an Uzi.
Seconds later, he was gunned down after she lost control of the submachine gun. Mr Charles Vacca was shot in the head when the Uzi recoiled, sending "the weapon over her head," a Mohave County Sheriff's Officer said.
The 39-year-old was airlifted to a Las Vegas hospital but died at 9pm (US time) on Monday, the New York Daily News reported.
Mr Sam Scarmardo, manager of the Arizona Last Stop gun range, said that the girl's parents were filming the session with their mobile phones when the accident happened in the morning.
Edited footage of the incident, which was released by police, shows Mr Vacca instructing the girl, 9, to hold the Uzi, a weapon designed in the 1950s, with both hands at all times.
Mr Vacca is heard telling her: "We have to keep that held in, otherwise the gun won't fire, okay?
"Turn this leg forward, there you go, just like that. All right, go ahead and give me one shot."
His last words before the girl fires off the gun in automatic mode were "All right, full auto".
The video cuts out just before she loses her two-handed grip on the weapon and it pulls to her left.
Police examined the phones as part of their investigations, Mr Scarmardo said.
Mohave County Sheriff Jim McCabe said the full video was "ghastly".
Sheriff McCabe said Mr Vacca, who suffered more than one gunshot to the head, "just dropped".
He told the Las Vegas Review Journal that no charges will be filed because the shooting range is licensed and legal.
The range was closed on Monday but reopened for business the next day.
Arizona gun laws require a person to be at least 18 years old to carry a firearm, but the laws do not apply on private property or if the minor is accompanied by a parent or a certified instructor, the Daily Mail reported
This article was first published on Aug 28, 2014.
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