The number and the lethal nature of active shooter incidents in the U.S. are soaring in recent years, Attorney General Eric Holder said Monday in Philadelphia. Speaking with police chiefs there, Holder said there were an average of five active shooting incidents a year from 2000 to 2008 — but active shooter incidents have tripled since 2009. "We've seen at least 12 active shooter situations so far in 2013," Holder said. Holder also said the number of people killed in actives shootings is up nearly 150 percent. According to the Department of Homeland Security, an active shooter is "an individual actively engaged in killing or attempting to kill in a confined and populated area." Recent examples include the Sandy Hook Elementary School shooting in Newtown, Conn., and the Washington Navy Yard shooting at the nation's capital. Holder says the Justice Department has trained multiple local, state and federal agencies on how to respond, and many police departments are abandoning traditional contain-and-wait tactics as they grapple with the new numbers.