When officers arrived at a quarry they found that revelers ignited 80 pounds of Tannerite, an exploding compound used for firearms practice. The partiers told police they thought the quarry would be the safest place to detonate the massive explosions. “We heard this god-awful blast,” neighbor Sara Taglieri told NBC 10 Boston. “It knocked pictures off our walls … I’m all up for silliness and what not, but that was extreme.”