The assistant director on Alec Baldwin's film, "Rust," said he neglected to do a thorough check on a gun used before a fatal shooting on set.

An affidavit from the Santa Fe Sheriff's Office for a search warrant that was issued on Wednesday provided new details into the shooting last week, which left cinematographer Halyna Hutchins dead and director Joel Souza injured.

The document describes a series of checks that a prop gun used in the film by Baldwin was supposed to undergo.

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Dave Halls, the movie's assistant director, told authorities about the safety protocol on the set, according to the search warrant affidavit.

"[Halls] advised when [head armorer Hannah Gutierrez-Reed] showed him the firearm before continuing rehearsal, he could only remember seeing three rounds. He advised he should have checked all of them, but didn't, and couldn't recall if she spun the drum."

While Gutierrez-Reed said that no live ammunition was "ever kept on set," the Santa Fe County Sheriff's Office said in a Wednesday news conference that the projectile that struck Souza was considered to be a "live round that was fired from the revolver" by Baldwin.

Authorities also said they found 500 rounds of ammunition on the set, which included a "mix of blanks, dummy rounds and what we are suspecting [are] live rounds."

A cameraman, Reid Russel, interviewed as part of the affidavit and described as standing next to Souza and Hutchins when the shooting occurred, told police that Baldwin "had been very careful" handling the firearm on the movie's set.

Noting an earlier part of the movie that the 63-year-old actor had filmed, Russel said Baldwin "made sure it was safe and that a child wasn't near him when they were discharging a firearm during that scene."

No one has been charged in the shooting, but Santa Fe County District Attorney Mary Carmack-Altwies said, "All options are on the table at this point."