Facebook site evacuated after mail tests positive for sarin

A Facebook mail processing warehouse near company headquarters at California, United States was evacuated on Monday as officials are working to determine what caused the mail to test positive for the nerve agent sarin.

Menlo Park Fire Marshal Jon Johnston said Monday that incoming mail undergoing routine processing by machine tested positive for sarin, but that there are no reports of injuries at the Silicon Valley site.

"Right now we don't have anybody that has any symptoms," he said. "We're just doing verification", he added. 

The FBI is assisting in the investigation, as is common in incidents such as this one.

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Facebook spokesman Anthony Harrison said four buildings were evacuated and that three buildings have been cleared for people to come back in. The suspicious package was delivered around 11 am to one of the company's mail rooms, he said.

"Authorities have not yet identified the substance found," Harrison wrote.

The Federal Centers for Disease Control and Prevention says sarin is a chemical warfare agent that is a clear, colorless, odorless and tasteless liquid. It can evaporate into the environment, prompting symptoms within seconds.

A drop of sarin on skin can cause sweating and muscle twitching, and exposure to large doses can result in paralysis and respiratory failure leading to death. The CDC says people who are mildly exposed usually recover completely.

In 1995, members of a doomsday cult unleashed a deadly sarin attack in the Tokyo subway system, killing 13 people and sickening more than 6,000. The cult leader, Shoko Asahara, and several followers were executed in 2018 for their roles in the crime.

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in December 2018, Facebook evacuated its headquarters after receiving an anonymous bomb threat that turned out to be a false alarm.

Facebook is updating its terms and services guidelines to clarify how it makes money from the personal information of its users.