This came in at Number 5 on ZenMonkeys:
Christmas Eve midnight mass in Temoaya, Mexico in 1953 had just finished. Three thousand worshippers were peacefully filing out when someone tripped over the wrong wire. There was a bright blue flash, and then total darkness. All sense of peace and goodwill toward men vanished as the crowd transformed into a panic-stricken mob stampeding from the sanctuary. By the time the lights came on a few minutes later, 23 people were dead and over 200 injured.