In the District of Columbia, an explosion kills seven men at the Washington Arsenal
At around two o'clock in the afternoon a small building at the Washington Arsenal where ammunition was being sorted was completely destroyed in a sudden explosion. Seven men were killed outright and several others suffered varying injuries. Fire fighters were able to control the flames and avoid any further disasters involving neighboring buildings housing ammunition. (By John Osborne)
"Fatal Explosion: Blowing Up of Ammunition at the Washington Arsenal," New York Times, December 19, 1865.