From the looks of it, this was a negligent discharge, not an "accidental" one. These terms get confused with a lot of todays reporting. If the individual causes the discharge because of something careless they did, that is negligence. That appears to be the case here. Glock's, (and all other pistols), don't go off by themselves. Another boneheaded firearms mistake. Lucky no one was killed. There seems to be a lot of this happening lately with cops and the like.