You might well think that the catastrophic destruction of firearms caused by shooters leaving their cleaning rods inside their guns was a rare occurrence, but you would be wrong. It happens far to often. These photos show what happens when a cleaning rod is left in a .338 Lapua Magnum rifle. A member of the SnipersHide forum reported that this KABOOM happened two benches down from him at the range. The shooter only sustained minor injuries. Two holes were punched in roof and pieces of the rifle were scattered around the range.
I am not sure exactly which demographic of the shooting community is responsible for this phenomenon, but it tends to be higher end bolt actions that are effected which makes me think it is veteran shooters and/or long range/competition shooters who are trying to extract the most accuracy from their guns by cleaning it between each string of shots. The extra weight of a cleaning rod, even a cheap light weight cleaning rod, significantly increases the pressure inside the barrel (it is essentially adding to the bullet weight at best, or jamming the bullet in the barrel at worst).
Thanks to Bill for the tip.