Package Sets Off Sarin Alarm at Facebook

An alarm went off as a machine screened packages at Facebook on Monday, alerting employees of the possible presence of sarin. Four buildings on the Menlo Park, California, campus were evacuated, CNBC reports; three were soon reopened. No employees were exposed to the poison, firefighters said, and a fire official told Business Insider that the alert could have been a false positive. Sarin is a man-made nerve agent used in chemical warfare. An investigation involving the FBI has begun, the AP reports. (More sarin stories.)