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Four injured as helicopter breaks up landing in Brazil

24 February 2012 Last updated at 03:02 GMT

An investigation is trying to find out why a rescue helicopter disintegrated shortly after landing in the northern state of Para in Brazil, injuring four people on board.

Amateur footage taken by the Para Fire Department showed how the aircraft came apart while vibrating on the ground.

Officials believe the helicopter experienced ground resonance, which happens when the rotor is working while the helicopter is on a level surface.