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At least 37 people have been killed and hundreds more injured in four bomb blasts on the Underground network and a double-decker bus in London. Here emergency services cordon off King's Cross station.

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Passengers on the underground begin to evacuate. The lucky ones are in a station...

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...others like Alexander Chadwick near Kings Cross have to walk through the tunnels to safety.

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At Aldgate, fire crews bring the injured up from the underground network...

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...but many are left dazed and shocked.

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In Tavistock Square, eyewitness Belinda Seabrook described an explosion rip through the bus.. (Photo: Toby Mason).

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"I was on the bus in front and heard an incredible bang, I turned round and half the double-decker bus was in the air," she said. (Photo by Mike Hughes)

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At Edgware Road station a man helps an injured woman away from the scene.

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Police across London are stretched as the underground network shuts down...

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..and people try to understand what is happening and make sure loved ones are safe.

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London's Emergency Plan is put into action as medical staff rush to the scene and hospitals are on full alert.

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UK Prime Minister Tony Blair said it was "reasonably clear" there had been a series of terrorist attacks. He said it was "particularly barbaric" that it was timed to coincide with the G8 summit, before flying back to London.