The 24-year-old armorer who worked on Rust gave a child actress a gun without checking it on a previous film set, two production sources who worked with her said.
The two sources told The Daily Beast that Hannah Gutierrez-Reed had allegedly given an 11-year-old actress a gun without checking it properly while on the set of the Nicholas Cage film, The Old Way.
'There were a couple times she was loading the blanks and doing it in a fashion that we thought was unsafe,' one of the sources said.
'She was a bit careless with the guns, waving it around every now and again.'
A search warrant released Friday said that Gutierrez-Reed laid out three prop guns on a cart outside the filming location, and first assistant director Dave Halls grabbed the gun from the cart and brought it inside to Alec Baldwin, unaware that it was loaded with live rounds.
'Cold gun!' shouted Halls before handing the gun to Baldwin, using the phrase to signal to cast and crew that the gun was safe to fire for the scene, the warrant said.
Seconds later, filming a scene inside an Old West-style church, Baldwin apparently aimed towards the camera and pulled the trigger, accidentally killing Halyna Hutchins as she filmed him, and injuring director Joel Souza, who stood behind her.
Sources on the set of Rust said the incident that killed cinematographer Halyna Hutchins could be tied to the armorer, Hannah Gutierrez-Reed
The colt pistol accidentally went off and pierced Halyna Hutchin's chest on Thursday
An inconsolable Alec Baldwin is shown outside the Santa Fe County Sheriff's Office after accidentally shooting and killing the cinematographer
Sources on the Rust set have said the fatal incident that killed Hutchins, 42, and injured Souza, 48, was a result of production failings from top to bottom.
They added that assistant director Halls, who handed the gun to Baldwin and told him it was safe, should have checked the weapon.
'He's supposed to be our last line of defense and he failed us,' one of the sources on set said. 'He's the last person that's supposed to look at that firearm.'
A Rust production source told The Daily Beast that there were at least two previous incidents of guns being accidentally discharged by other crewmember on set before Thursday's tragic incident.
The source described Gutierrez-Reed as 'inexperienced and green.'
Gutierrez-Reed had previously admitted she wasn't sure she was ready for the job on The Old Way in an interview before filming started.
Hannah Gutierrez-Reed, the 24-year-old head armorer in charge of guns on Alec Baldwin film said she 'wasn't sure she was ready' for the job in an interview before filming began
An aerial view of the Bonanza Creek Ranch in Santa Fe, where the movie was being filmed. Workers had been protesting over the fact production wouldn't pay for them to stay in hotels and motels in Santa Fe, instead forcing them to drive an hour to Albuquerque
A search warrant released Friday said that Gutierrez-Reed laid out three prop guns on a cart outside the filming location, and first assistant director Dave Halls (pictured) grabbed the gun from the cart and brought it inside to Alec Baldwin, unaware that it was loaded with live rounds
'I almost didn't take the job because I wasn't sure if I was ready, but doing it, it went really smoothly,' Hannah Gutierrez-Reed said in a podcast interview last month after leading the firearms department for The Old Way, starring Nicolas Cage - her first time as head armorer.
She also admitted in the podcast interview she found loading blanks into a gun 'the scariest' thing because she did not know how to do it and had sought help from her father, legendary gunsmith Thell Reed, to get over the fear.
It comes as the film crew revealed they walked off set hours before the fatal accident over safety fears after firearms were accidentally discharged three times - including once by Baldwin's stunt double who had been told the gun was not loaded, and twice in a closed cabin.
Neither Halls nor Gutierrez-Reed immediately returned messages from DailyMail.com late on Friday. Neither has been charged or named as a criminal suspect in the case, though a police investigation is ongoing.
The gun that fired the fatal shot was a vintage-style Colt revolver, DailyMail.com has exclusively learned.
After the shooting, the armorer took possession of the gun and a spent casing, which were turned over to police, along with other prop guns and ammunition used on the set.
Baldwin also changed out of the Western costume he was wearing, which was stained with blood, and turned it over to police.
The warrant does not reveal the model or caliber of the prop gun that fired the fatal bullet, but the film is set in the Old West of the 1880s and DailyMail.com has learned it was a Colt.
The warrant was obtained Friday so that investigators could document the scene at the ranch where the shooting took place.
Unionized workers had walked off the set hours before the fatal shooting, after they complained about long hours, shoddy conditions and another safety incident days earlier involving 'two misfires' of a prop weapon.
A yet-unnamed prop master who oversaw the gun used in the fatal shooting was a non-union worker who was 'just brought in' to replace the workers who left over safety concerns, a source involved in the movie told the New York Post.
It's unclear whether Gutierrez-Reed, the armorer, had recently joined the production, or was one of the crew members who stayed behind after the walk-off.
However, a link in her Instagram bio points to an article about Rust from May, suggesting she had been attached to the production for some time.
Unionized employees had been complaining about the fact they had to stay overnight in Albuquerque - an hour's drive from the set - and not Sante Fe because production wouldn't pay for their hotels, according to sources cited by The Los Angeles Times and multiple social media posts by film and TV insiders.
When they turned up to set to clear their things on Thursday, they found they'd been replaced by locals.
It begs the question of who