'Rookie' changes prop weapons policy following fatal shooting on 'Rust' set - CNN

Weapons expert Ben Simmons previously explained to CNN that typically three types of prop guns are used on set -- completely fake firearms (that looks real but can't fire anything), deactivated firearms and real firearms, which are loaded with blanks and mimic actual shooting, from flash to recoil.

Over the weekend, it was reported that actor Alec Baldwin had been given a prop firearm during a rehearsal and been told it was a so-called "cold gun," a term meant to indicate the weapon didn't have live rounds, according to an affidavit for a search warrant for the movie set filed by the Santa Fe County Sheriff's Office and obtained by CNN affiliate KOAT.

According to the affidavit, Baldwin was handed one of three prop guns by assistant director David Halls that were set up in a cart by an armorer for the movie "Rust."

Halls did not know there were "live rounds" in the gun, the affidavit said.

It has not yet been determined what the gun Baldwin fired was loaded with, according to Santa Fe County Sheriff's Office.