There's a deadly sarin substance in the Facebook building

Officials announced that “have two possible exposures, but so far they have not shown symptoms or signs” said the head of firefighters at Menlo Park, where the Facebook building is located.

Two buildings have been evacuated, writes the American newspaper San Francisco Chronicle. Federal Bureau of Investigation agents (FBI) from the San Francisco branch have come up with an emergency team for dangerous materials, according to Federal Bureau spokesman Reuters reports.

Social media representatives Facebook have said a suspicious package was delivered by mail to the Facebook delivery centre. Four buildings have been evacuated, but later three have been estimated to be safe.

The nervous agent Sarin has already been used as a chemical weapon that undermines the human nervous system.