Land mine "donated" to Good Will

Someone put a land mine in a Goodwill donation box at an Arvada, Colorado strip mall. A bomb squad dealt with the mine; it's unknown whether it was live or not. According to the Associated Press, the package, a "rectangular, olive-green box with the words 'Front Toward Enemy'" worried Goodwill workers when they saw it. "Land mine left in Goodwill donation box"

UPDATE: In the comments, folks have correctly identified the device as a Claymore Antipersonnel Mine.