Surveillance video shows moment before Amtrak train derailment in Philadelphia

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PHILADELPHIA — CNN’s Sara Sidner reports on the surveillance video that caught images from the Amtrak train derailment in Philadelphia.

The surveillance video may help investigators figure out why an Amtrak train derailed in Philadelphia Tuesday night.

The impact tore cars apart and an engine and all seven cars derailed.

Six people are dead and at least 200 others were hurt.

The cause of the accident is not immediately known.