Jeffrey Michael Kelly, 60, was also arrested on suspicion of leaving white powder on political signs in Ahwatukee, according to Tempe police.

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.

TEMPE, Ariz. — A 60-year-old man suspected of shooting at a Democratic National Committee office over the last two months and hanging suspicious bags of white powder from political signs in a nearby village had over 120 guns and over 250,000 rounds of ammunition in his home and was preparing for a "mass casualty" act, according to prosecutors.

The suspect also allegedly hung suspicious bags of white powder from political signs in a nearby village, police say.

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.