An assistant director on the film Rust, the site of a fatal shooting involving the actor Alec Baldwin last week, told investigators he didnt thoroughly check all the rounds in a prop gun before it was used to rehearse a scene, according to multiple media reports.

The director, Dave Halls, was supposed to check all of the rounds before handing the gun to Baldwin and saying that it was cold, meaning there were no live rounds inside and that it was safe to use as a prop. Failure to do so is a major breach in safety protocol, The Los Angeles Times reported .

The films armorer, Hannah Gutierrez-Reed, also reportedly opened the gun for him to inspect, but Halls said he couldnt remember if she spun the drum of the firearm to fully inspect it.

He advised he should have checked all of them, but didnt, and couldnt recall if she spun the drum, according to an affidavit obtained by The New York Times.

The films cinematographer, Halyna Hutchins, was shot and killed during the rehearsal. Its director, Joel Souza, was wounded.

Officials first said Wednesday that a lead bullet had been recovered from Souzas shoulder and that they believed they had recovered more live rounds on the set of the film. The affidavit filed by investigators said they recovered about 500 rounds of ammunition from the set, which they believe to be a mixture of blanks, dummy rounds and what we are suspecting were live rounds.

Dummy rounds are designed to look like real bullets for close-up shots, although they contain no gunpowder. They typically have a small hole in them or an indentation showing they are not live, but The Los Angeles Times noted they require serious safety measures because they more closely resemble a real bullet than a blank.

The affidavit also said that after the accidental shooting, Halls took the gun to Reed to inspect. When she opened it, investigators said, he saw at least four dummy casings with holes in the sides, and one without the hole.

He advised this did not have the cap on it and was just the casing, the affidavit added.

An unnamed crew member told the newspaper that having live rounds on set was so far off the realm of whats wrong and bad, adding that anyone caught with that type of ammunition while filming scenes with guns would be fired immediately.

Since the fatal incident, questions about blame and responsibility have swirled. Investigators are probing the roles of Halls and others on set, although no charges have been filed.

This is a developing story. Please check back for updates.