The Hennepin County Sheriff's Office says an investigation is underway after an AR-15 semiautomatic rifle with a 100-round drum magazine was recovered.

Colorado shooter used shotgun, assault-style rifle with 100-round drum magazine. July 20, 2012, 10:49 PM EDT. ... 3,000 rounds of .40-caliber ammunition for the Glock handguns.

A friend of Connor Betts accused of providing the Dayton, Ohio, shooter with the body armor and a 100-round double drum magazine used during his attack is facing federal firearms charges.