Police found a huge stash of guns and ammunition in his home, leading prosecutors to believe he was planning a "mass casualty" event.

An Arizona prosecutor said the man arrested in the three-time shooting of a Democratic National Committee office in suburban Phoenix had more than 120 guns and over 250,000 rounds of ammunition in his home,

Arizona investigators surveilling the man accused of shooting at the Democratic National Committee office in a suburb of Phoenix saw him posting political signs with bags of a white, powdery substance attached,