Police found an "enormous amount of bullets" on the set where cinematographer Halyna Hutchins was fatally shot with what has been described as a "prop gun" until now.
According to Santa Fe County district attorney Mary Carmack-Altwies in an interview with The New York Times, it is incorrect to refer to the weapon handled by actor Alec Baldwin as a "prop" for the western Rust. He also said criminal charges have not been ruled out in the investigation.
"It was a legit gun," Carmack-Altwies told the paper. "It was an antique era appropriate gun."
Furthermore, on the set surrounding the small church where Hutchins was killed while Baldwin was rehearsing a scene, "an enormous amount of bullets" was found.
The prosecutor said investigations into the nature of the ammunition located at the scene were under way.
"We need to find out what kinds they were," Carmack-Altwies explained.
It comes after reports that crew members were using guns with live ammunition for target practice hours before the incident, which Carmack-Altwies said were "unconfirmed."
Founder and CEO of entertainment site The Wrap, Sharon Waxman, told CNN on Monday that sources from the Rust set revealed crew members had been engaged in a pastime called "plinking" hours before Hutchins was shot.
According to Waxman, one of the loaded guns used was later handed to Baldwin, who fired the shot that killed mother-of-one Hutchins, 42, and injured director Joel Souza while "practising a cross draw", The Wrap reported.
"They go out into the rural areas and they shoot at beer cans. This is with live ammunition. We learned that this happened the morning of the day that Halyna Hutchins was killed," Waxman said, adding that it was a common pastime on film sets.
When asked by The Wrap for comment on the claims, Rust producers referred back to their previous statement sent to media outlets.
"The safety of our cast and crew is the top priority of Rust Productions and everyone associated with the company," it read.
"Though we were not made aware of any official complaints concerning weapon or prop safety on set, we will be conducting an internal review of our procedures while production is shut down.
"We will continue to co-operate with the Santa Fe authorities in their investigation and offer mental health services to the cast and crew during this tragic time."
Director Souza, who was injured in the shoulder, told investigators the weapon went off as Baldwin was practising drawing his gun, according to an affidavit for a search warrant.
He said Baldwin was "sitting in a pew in a church building setting, and he was practising a cross draw," the affidavit said.
Souza was looking over Hutchins' shoulder "when he heard what sounded like a whip and then a loud pop," according to the affidavit.
"Joel then vaguely remembers (Hutchins) complaining about her stomach and grabbing her midsection," it reads.
"Joel also said (Hutchins) began to stumble backwards and she was assisted to the ground.
"Joel explained that he was bleeding from his shoulder and he could see blood on Halyna."
He also confirmed to an investigator that he heard the term "cold gun" on set, meaning the firearm should not have been loaded and was safe for use.
Souza said three people had been handling the firearms for scenes – explaining they were checked by the armourer and first assistant director before given to the actor using them.
Meanwhile, separate from the affidavit, the chief electrician on the movie also shared devastating details over Hutchins' last moments, including holding her in his arms "while she was dying".