Facebook evacuated after hazardous material call

Two people were exposed to a possibly hazardous substance Monday at a Facebook shipping facility in Menlo Park where a suspicious package was discovered, officials said.

The Menlo Park Fire Protection District received a hazardous material report at 10:58 a.m. at the facility at 1195 Hamilton Court. FBI investigators and a hazardous materials crew were dispatched to the scene.

Late Monday afternoon, crews from San Mateo County and the National Guard, all wearing protective gear, entered the building to conduct tests on the substance. But the first round of tests, completed around 8 p.m., was inconclusive, said Jon Johnston, the Menlo Park fire marshal.

A fourmember crew was sent back for more detailed tests, including a chemical analysis. Results from those tests were not expected for several more hours.

Facebook officials said the suspicious package was delivered to one of the company’s mail rooms. Four buildings were evacuated as officials investigated, but three were cleared for people to return Monday afternoon, Facebook spokesman Anthony Harrison

said.

“The safety of our employees is our top priority,” he said.

Officials would not say what the substance might be, but a fire dispatcher relayed over the police scanner that Facebook personnel had reported detecting sarin gas, a powerful nerve agent.

Five people were in the building when the package was discovered and two of them may have been exposed to the substance, Johnston said. No one showed any symptoms of an illness, he said. As of 10 p.m., both individuals were still on site and being monitored, though they remained symptomfree.

In addition to local police and fire officials, the FBI and the National Guard, U.S. Postal Inspection Service investigators were also on scene Monday. Officials partially shut down the parking lot and roads within the business complex with caution tape. Facebook officials sent pizzas to the emergency responders at the scene.

Earlier in the day, Johnston said investigators were waiting for “other resources,” including special testing equipment, to start studying the substance. Johnston said later Monday that the investigation was focused on a specific mail bag.

He said the situation was “very stressful” for the crews conducting tests inside the building.

“They are wearing full breathing apparatus that they have with them,” he said. “There is no breathing through that gear. And so there is a lot of sweating.”

Sarin is an odorless, colorless liquid that can be used as a nerve agent, according to the Centers for Disease Control and Prevention. It is not found naturally in the environment. People exposed to sarin may experience symptoms such as nausea, confusion, sweating, muscle twitching, loss of consciousness, convulsions, paralysis and respiratory failure.

Facebook bought the shipping warehouse, along with 20 nearby buildings, for $395 million in 2015 from an affiliate of Prologis, a San Francisco industrial landlord, according to property records.

This year, the social media giant proposed a massive real estate project on the site called Willow Village. Chronicle staff writers Bob

Egelko and Roland Li contributed to this report.