If an accident, and especially if it involved a long gun, it may even have been a case of peering down the barrel after a hang-fire, only to have the round go off a second later.  There is at least one very clear YouTube video of a near fatality due to this.

Again, if an accident, it reinforces the strict rule to always check if a gun is unloaded no matter who hands it to you - even if it was Jesus Christ himself.

One can never tell how closely the wings of the Angel of Death will flutter by you.  There is a true story involving a customer in a gun shop inspecting a used deer rifle before purchase.  He shouldered the 30-06 and looked through its telescopic sight at an open-air market across the street, just by chance settling the crosshairs on a man handling produce.  "Man, I could put one right in that guy's ear!" he said to the store clerk standing across the counter.  Then he worked the bolt to cock the action thinking to try the trigger pull - and ejected live soft-point round.