Did hear stories of a fatality at an unamed site on a 14th birthday party. Although it wasn't a playing accident more of an equipment malfunction. The fatality was supposedly the 14 year old boys mother who had arranged the party. During spectating a bottle had supposedly blown off one of the rental guns or from the reg and struck the mother in the side of the head. Apparently died as the paramedics tended to her.
I have tried looking up any info but this seems to be merely Chinese whispers at this point as there isn't as much as a newspaper article on the incident.
That will be this one:
http://www.automags.org/forums/showthread.php?125502-Woman-killed-by-paintball-marker-tank
Co2 cylinder unscrewed from its pin valve
(The equivalent of an air cylinder unscrewing from its regulator)
The safety features guard us from this by having tapered threads in cylinder regulators so the air pressure is released before it unscrews enough to come off, or a hole in co2 valves
They were not always made that way, the above linked thread gives a lot of speculation
What likely is the co2 regulator was not tight enough, and either was too old for the features or may have been loctited and blocked the exhaust hole etc