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CIA left explosive material on Loudoun school bus after training exercise - The Washington Post: "The CIA left “explosive training material” under the hood of a Loudoun County school bus after a training exercise last week, a bus that was used to ferry elementary and high school students to and from school on Monday and Tuesday with the material still sitting in the engine compartment, according to the CIA and Loudoun County officials.

The Loudoun County Sheriff’s Office and the CIA said in statements Thursday that the explosive material was left behind after a training exercise at Briar Woods High School during spring break...

Authorities held a joint training program at Briar Woods from March 21 to 24.  Loudoun schools spokesman Wayde Byard said the CIA indicated the nature of the material but asked the school system not to disclose it. 

Byard described it as a “putty-type” material designed for use on the battlefield and which requires a special detonator; such putty, or plastic, explosives — including the well-known C-4 — are used in demolition and are considered stable. Byard said law enforcement agencies use school facilities on occasion to conduct realistic training exercises, including active-shooter drills. As part of last week’s training exercise, CIA trainers placed explosive material into the engine compartment of a school bus on Thursday to test a dog’s ability to sniff it out. They also placed the material in parts of the school."