[mmcwilliams]

Here is your second incident:

http://en.wikipedia.org/wiki/Mitchell_Johnson_and_Andrew_Gol...

Here's your third: #59 in your first link. Here's your fourth: #67 in your first link.

We know of the incidents stopped, but so many of those in your links ended by the killers' own hand. In almost all of the cases, however, these are mass murderers with guns.