Reactor Containment Dome Building Explodes (Japan)

Bad - building explodes
Worse - exploding building is part of a nuclear power plant

My understanding is that the explosion was caused by a buildup of hydrogen and not the reactor going critical which would have been catastrophic. That does not mean they are out of the woods yet, and there have been people exposed. If they can not get the reactors under control the negative effects from the earthquake and tsunami could get exponentially worse.

Video embedded below.