EDGEWOOD, Md. (AP) — Officials at Aberdeen Proving Ground have halted a demolition project after trace amounts of a World War I chemical warfare agent were found at the site.

A spokeswoman told The Baltimore Sun on Thursday that debris from the building demolition site contained tiny amounts of lewisite in the pipes. The chemical agent can cause skin blisters and lung damage.

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Officials say no one was hurt by the chemical agent. They say a worker who detected the chemical odor after a pipe was broken Tuesday was found not to have had any exposure.

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They say workers are covering the demolition debris. The excavation of concrete slabs and underground pipes has been halted while officials consider how to proceed.

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