MENLO PARK (CBS SF) — Hazardous materials specialists from the California National Guard’s 95th Civil Support Team have been called in to assess a suspicious package shipped to Facebook’s facilities in Menlo Park that may have been contaminated with a chemical weapon.

“They specialize specifically in chemical, biological and radiological detection,” Menlo Park Fire Protection District Fire Chief Harold Schapelhouman said Monday evening.

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“We’re not saying there’s anything there, but out of an abundance of caution, this is the right group to bring in to make sure there isn’t a problem,” Schapelhouman said.

Around 11 a.m. Monday morning, screeners testing incoming mail at 1005 Hamilton Ave. found the presence of a material suspected to be the nerve agent sarin. The package was re-tested twice, with one positive and one negative result.

Hazmat crews entered the mail room a second time with more sophisticated equipment Monday night. It will take a long time to process samples, so results are expected after midnight.

“A large bag of mail that we’re just trying to determine whether or not there’s something of risk there or not. Right now, it’s inconclusive and we want to be able to determine whether it’s something we need to be concerned with,” said Menlo Park Fire Protection District Fire Marshal Jon Johnston.

The FBI has been called in to assist with the case. Former FBI agent Jeff Harp trained to conduct law enforcement operations to handle and prepare for sarin gas.

“The threats that have come in to these companies, the actual violent acts that have been committed at these companies, they’ve become more and more serious about screening packages coming in to the mailroom,” said Jeff Harp, KPIX 5 security analyst.

“A lot of places don’t even do it on site, they do it offsite just in the event, there is something that they find.”

Facebook evacuated a total of four buildings, three of which have since been cleared to repopulate, according to Facebook spokesman Anthony Harrison, but authorities have not yet positively identified the suspicious substance in question.

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Two people handled the package in question, but there are no medical issues to report, and these individuals are not thought to have been exposed to any dangerous materials.

Schapelhouman said it’s not yet clear whether this situation is a false alarm or a serious incident.

“We don’t know yet. Either way it’s contained to the structure of origin,” Schapelhouman said. “There’s no threat to the local community whatsoever right now.”

“Everything that can be done is being done,” he added.

Schapelhouman credited Facebook for having the technology to do the screening that keeps employees safe.

Sarin gas is a clear, colorless nerve agent with no taste or odor that can occur in liquid or vapor form, according to the federal Centers for Disease Control and Prevention.

Exposure is possible through skin or eye contact, as well as inhalation. For more information, people can go to


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