In the hours since actor and producer Alec Baldwin shot two people on a film set in New Mexico on Thursday, killing cinematographer Halyna Hutchins, attention has turned to the prop firearm used while he was in character.

Baldwin was shooting a scene on the set of the western film “Rust” when he discharged a firearm that struck Hutchins, 42, and director Joel Souza, 48. Both were rushed to area hospitals, where Hutchins was pronounced dead, officials said. “Rust” actress Frances Fisher tweeted Friday that Souza had been released after being treated for his injury.

As firearms experts, writers and producers wondered aloud how this happened, there’s a renewed spotlight on prop guns, their history in film and TV, and why firearms are still showing up on set. While some producers insist on using prop guns with blanks to closely capture the sound and look of a real gun firing, others have been calling for them to be banished from film sets, saying that computer-generated imaging offers a safer alternative.

“There’s no reason to have guns loaded with blanks or anything on set anymore,” tweeted director Craig Zobel, whose credits include the 2020 film “The Hunt” and the HBO series “Mare of Easttown.” “Should just be fully outlawed. There’s computers now.”

A day after actor Alec Baldwin fatally shot a cinematographer on a film set in New Mexico, The Post spoke to a prop expert about how prop guns are used. (Allie Caren, Ashleigh Joplin, Nicki DeMarco/The Washington Post)

Juan Rios, a spokesperson for the Santa Fe County Sheriff’s Office, said detectives are investigating what type of projectile discharged from the prop gun, as well as how many firearms were on set and how they were handled. Rios said he expects the sheriff’s office will have more information early next week.

So, what is a prop gun? While it’s thought of as a nonfunctional weapon often used in theater productions, the term also refers to real guns on TV and film sets that are loaded with blank cartridges, which are essentially modified bullets.

“Prop guns are guns,” tweeted TV writer David Slack, whose credits include “Magnum P.I.” and “Person of Interest.” “Blanks have real gunpowder in them. They can injure or kill — and they have. If you’re ever on a set where prop guns are treated without proper caution and safe handling, walk away.”

A regular gun cartridge has a shell casing holding a propellant powder. When a normal gun is fired, the propellant is ignited and the bullet attached to the front of the shell is activated. In comparison, the blanks used in prop guns usually have a material such as paper, cotton or wax attached to the front of the shell instead of a metal projectile.

“They’re supposed to be built in a way to prevent them from even being able to accept real ammunition,” tweeted Stephen Gutowski, a gun-safety instructor and firearms reporter for TheReload.com.

Bill Davis, a Georgia-based weapons expert who has worked on hundreds of film and television productions, told The Washington Post that the safety protocols in place on nearly all sets do a great job protecting the actors and crew. Prop guns are usually safeguarded by someone who specializes in firearms in a production or the props department, he said.

“If you follow the rules, you’re going to have a nice, safe day,” Davis said.

These prop guns with blanks are used on Hollywood sets because of the authenticity they add to filming. Firing a blank with a prop gun will produce three things that computer-generated imagery sometimes struggles to match: a recoil, a loud bang and a muzzle flash, which is the light created when the propellant powder combusts. Dave Brown, a Canada-based professional firearms instructor who has worked on films and TV shows, wrote in American Cinematographer magazine that although visual effects and CGI can help with close-range gunshots that cannot be filmed safely, firing guns with blanks makes a scene look as real as possible.

“Blanks help contribute to the authenticity of a scene in ways that cannot be achieved in any other manner,” Brown wrote in 2019. “If the cinematographer is there to paint a story with light and framing, firearms experts are there to enhance a story with drama and excitement.”

Blanks can nonetheless still be dangerous: Even if there isn’t a bullet inside, anything near the end of the prop gun’s barrel can be a threat thanks to the muzzle flash and superheated gas expelled from it. As a result, significant, and even fatal, damage can be done when the trigger is pulled.

“They can kill you, but only if it’s a contact wound to the skull or a carotid artery, something that can kill you,” Davis said. “But they are not designed to kill.”

Directors such as Zobel have shifted to CGI instead; he noted that the gunfire featured in “Mare of Easttown,” the crime drama starring Kate Winslet, was all digital.

“You can probably tell, but who cares?” he said. “It’s an unnecessary risk.”

There is a history of prop-gun incidents resulting in deaths on movie sets. Jon-Erik Hexum died days after accidentally shooting himself in the head with a prop gun on the set of the CBS show “Cover Up” in 1984. Authorities said at the time that Hexum, 26, was pretending to play Russian roulette with a .44 Magnum revolver when the gun fired a blank cartridge that killed him.

In 1993, about nine years later, Brandon Lee, the 28-year-old actor and son of actor and martial artist Bruce Lee, died on the set of the film “The Crow” after actor Michael Massee shot him in the abdomen. The prop gun used, which was supposed to be loaded with blank and “dummy” rounds, was somehow loaded with a .44-caliber bullet, police said. The North Carolina district attorney later said the shooting was caused by the crew’s negligence.

Davis emphasizes that the prop guns used on set should be considered dangerous and only handled by a legitimate firearms expert. Noting that Baldwin was filming a Western movie, he said the weapons from that time period are some of the “most dangerous guns to use on a set” because they do not have gas restrictors in their barrels.

“Any gun guy who is worth their salt would have said to any actor, ‘Do not point the gun at any living thing,’” Davis told The Post.

As the news of Thursday’s shooting spread, fans and those in the film and television industry shared why incidents such as the one in New Mexico should be avoidable. Podcast host Noah Kulwin asked, “Is it a prop gun if it shoots and kills someone? Isn’t that just a real gun?” One person shared a behind-the-scenes clip of the 2018 film “Halloween” that showed actress Jamie Lee Curtis shooting a prop gun with a barrier protecting the camera operator from any potential tragedy.

While it remains unclear what happened on set and the investigation is still ongoing, the incident has already sparked a debate about safety on set.

“Everyone who has witnessed the safety protocols/safety meetings/barrel checks that go into a prop gun being used in a production is screaming HOW … did this happen,” actress and writer June Diane Raphae wrote on Twitter.

Jaclyn Peiser contributed to this report.