William Celli, 55, is being held at the Contra Costa County Jail on a $525,000 bond after an anonymous caller tipped police off about Celli’s activities. The owner of a plumbing company was charged with possessing an explosive device and making criminal threats.

Anonymous recently published a YouTube video declaring war on ISIS following last week's terrorist attacks in Paris, and it looks like the hacktivist group may have taken its first steps towards battle.