He had a past conviction for making a pipe bomb. Klebold scared his coworkers by once bringing a pipe bomb into work. On 27 September, four soldiers were injured by pipe bomb explosions. Such explosives also do not require the containment of a pipe bomb. The blast was caused by a cellphone-triggered pipe bomb. A Pipe Bomb announced that it was ending. A warning circular picturing a homemade pipe bomb similar to the bomber's was distributed. The vehicle was later found to contain a live pipe bomb. Three Catholic-owned homes on Newington Avenue were badly damaged in a loyalist pipe bomb attack. McCarthy tweeted this a day after a pipe bomb was delivered to Soros' home. On the evening of July 12, Morales was constructing a pipe bomb. Hector sets off Walter's homemade pipe bomb, killing himself, Tyrus and Gus.