This article has been updated. Actor Alec Baldwin will be charged with involuntary manslaughter over the shooting of cinematographer Halyna Hutchins, who was killed on a film set when he fired a prop gun.

The tragic news of actor Alec Baldwin killing one person and injuring another on the set of a western movie has shocked the world. The incident involved a prop gun, not a ‘real’ gun, but prop guns can also kill

In fact, it’s not the first time prop guns have killed people on set — and it’s important to be aware that guns shooting blanks can also be dangerous.

Firing blanks

A gun that has no ammunition (as in, neither bullets nor blanks) isn’t really dangerous. But guns using blanks do have a projectile — it’s just that instead of a bullet, they use wads of paper, plastic, felt, or cotton. This is to make shooting the gun more realistic and produce a flame.

When shooting at a distance, these wads don’t do anything and are harmless.

The thing about a bullet is that it’s built from a very dense material. This dense material (typically a heavy metal) allows it to fly straight and maintain momentum, as momentum depends on mass and speed. Replace a normal bullet with a wad of paper and you end up with something much lighter that quickly loses momentum. That’s why blanks are harmless from a distance.

But when shot from close range, things can be very different.

In 1984, the actor Jon-Erik Hexums made a bad joke. He put a gun loaded with blanks to his head, and joking about delays to filming, played Russian roulette and pulled the trigger. It was enough to kill him, because the gun was so close.

Blanks should never be shot within a few meters because they can cause real damage — even fatal. To make matters even worse, blanks sometimes contain more gunpowder than real bullets, to make a more impressive ‘bang’. In 1988, Bruce Willis lost two-thirds of his hearing while filming Die Hard after firing a gun loaded with extra-loud blanks.

TV writer David Slack, known among others for his work on Law & Order and Transformers: Prime took to Twitter to point out that guns shooting blanks are still guns. There are several different types, all with their advantages and potential risks, but they are all dangerous.

Some of the most infamous accidents with blanks on movie sets involve someone screwing up and actually leaving real bullets in instead of blanks. The first such recorded incident dates from 1915, when during filming a scene of The Captive, one of the extras inadvertently left a live round in his rifle and shot another extra in the head, instantly killing them.

More recently, in 1993, American actor and martial artist Brandon Lee was accidentally shot and killed while filming The Crow after a gun intended to fire blanks contained a real bullet.

It’s not yet clear just what happened on the set with Alec Baldwin and if the events involved real bullets or just blanks.

Movies can be dangerous, and guns especially so

There’s a surprisingly long list of serious injuries that took place on movie sets. From gunshots to stunt accidents and anything you can imagine, movie sets seem to be risky business. Every year, there seems to be at least one movie-associated fatality, whereas from 1980 to 1990, there were no fewer than 37 fatal accidents during stunts.

Ultimately, exhausted, overworked movie technicians doing 12-14 hour shifts are trusted to ensure the safety of everyone on set — and mistakes can happen. Thomas Jr, a member of IATSE (International Alliance of Theatrical Stage Employees) pointed out this risk on Twitter.

In an article in The Conversation, Australian researchers Christopher Gist and Sarah Mayberry also expressed the importance of being very careful when working with guns on set:

“Any moment you are using weapons on set, you must treat them with the utmost respect. Safety has to be paramount. In Australia, guns are so rarely handled we found they are highly respected: people are very conscious of the weapon.”

For something like this to have happened, though, it likely means multiple people messed up, TV and cinema camera technician Darwin Brandis also pointed out on Twitter.

For now, though, we don’t really know what happened. An investigation is currently underway with detectives investigating how the projectile was discharged and what type of projectile it was.