Oklahoma City Bombing: The Albert P. Murrah Federal Building shows the devastation caused by a fuel and fertilizer truck bomb on April 19, 1995. The blast killed 168 people and injured more than 500.
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In this 2010 photo, coal miner Terry Cooper, left, embraces his wife Michelle, daughter Tera and son Justin, during a vigil to honor the coal miners that were killed in Montcoal, W. Va.
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Mine helmets and painted crosses sat at the entrance to Massey Energy's Upper Big Branch coal mine on April 5, as a memorial to the 29 miners killed there one year earlier.