When we hear about "blanks" in a gun, the word that comes to mind is "harmless". Yes a blank makes a loud bang, but no bullet comes out so blanks are harmless.
But people have actually been killed by blanks, as described in this video about the death of John Erik Hexum:
Summary version: Hexum pointed a gun containing a blank to his head and fired the gun. The impact of the paper wadding in the blank and/or the pressure wave leaving the barrel shattered his skull, caused major blood loss in the brain and left him brain dead. The only good news that came from this story is the fact that several of his organs, including his heart, were used in transplant operations.
Watch the ultraslow-motion view of a gun firing in this video (it gets slower as the video goes along). Notice the cloud of high-pressure gas that precedes and follows the bullet as it leaves the barrel. Right next to your head there is tremendous pressure in that cloud - enough to kill you:
The problem here is the fact that Hexum was holding a normal gun loaded with a blank cartridge. Today there are prop guns and starter pistols that are designed to shoot only blanks. Their barrels are plugged. Even so, the gun still needs to vent the gas from the blank cartridge. Caution is advised, as described on this page:
When blank-firing stage prop pistols are fired, gunpowder gas is vented forward and sideways through the front of the cylinder, NOT from the muzzle. This gas is hot, and may contain small particles of powder debris. At arm's length it dissipates harmlessly into the air, but if your hands, face or other parts of your body are in close proximity to the vent hole it can cause burns, cuts or abrasions.
So, if you are using a purposefully designed blank-firing pistol and you are clear of the vent holes, you would think that you you would be safe, right? Not true, as described in this article:
A low-budget indie film shooting inside a Long Island convenience store got a dose of real life drama last night when a passerby mistook a robbery scene for the real thing and called the cops. Twenty officers responded to the call, and when they arrived at the scene, they saw a man pointing a gun at another man behind the register. The director was filming from the back of the store with a small high-definition camera and no movie lights, so it was not immediately clear to cops that they were charging into an imaginary holdup with guns drawn.
The actor holding a fake gun was nearly killed by police holding real guns. Even fake guns can be very dangerous.
[[[Jump to previous PSA - You CANNOT make any kind of joke about blowing things up or murdering people]]]