French fire brigade members aid an injured individual near the Bataclan concert hall following fatal shootings in Paris. Christian Hartman/Reuters/Landov hide caption

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KABOOM! A NASA illustration of a gamma-ray burst. They occur, the space agency says, when "a massive star runs out of nuclear fuel, collapses under its own weight, and forms a black hole. The black hole then drives jets of particles that drill all the way through the collapsing star." hide caption

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Fire fighters and utility workers at the scene of a massive gas explosion and fire Tuesday night in Kansas City, Mo. Orlin Wagner/AP hide caption

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