(CNN) — 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,

An Arizona prosecutor said the man arrested in the 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, leading law enforcement to believe he may have been planning a mass casualty event.

Authorities said they found 120 guns and 250,000 rounds of ammunition when they raided Jeffrey Kelly's Arizona 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,

Authorities searching the home of a 60-year-old man accused of shooting at a Democratic National Committee office in Tempe, Arizona, discovered an extensive collection of weapons — including 120 guns,

The suspect was also arrested for allegedly hanging suspicious bags of white power from political signs lined with razor blades.