It's not guns, although at least knives don't usually cause mass slaughter.
However, what is it that leads to so much murderous violence?
Mr Allen was confirmed dead at the scene close to the Eclipse venue on Castle Canyke Road in Bodmin, Cornwall, following reports of a street brawl.
Seven men and women with suspected stab wounds were taken to hospital.
Police have been granted by magistrates more time to question a man, 24, in connection with their murder inquiry.
[bbc.com]