What is sarin gas, and how does it work?

Suspected Sarin gas vials are seen in a brief case at a site in Fallujah, Iraq, in 2004.
Suspected Sarin gas vials are seen in a brief case at a site in Fallujah, Iraq, in 2004.

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    What is sarin gas, and how does it work?

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CNN's Tom Foreman explains where sarin gas could have been used in Syria and what the deadly poison does to a person.