Earlier in the day, media reported that, according to Menlo Park fire district officials, a machine at the facility alerted employees that the package could contain the nerve agent Sarin.
"This morning, a package delivered to one of our mail rooms was deemed suspicious", Harrison said on Monday. "We evacuated four buildings and are conducting a thorough investigation in coordination with local authorities. Authorities have not yet identified the substance found. As of now, three of the evacuated buildings have been cleared for repopulation".
Fire officials say routine tests for chemicals detected the presence of sarin in a #Facebook mail facility. It’s possible that the detection is a false positive. We expect to get a briefing from @menlofire within the hour. Facebook officials have yet to comment. #ABC7Now pic.twitter.com/BcRnQePuYW— Chris Nguyen (@ChrisNguyenABC7) 1 июля 2019 г.
Harrison added that more information will be shared when it becomes available. Fire officials noted earlier that two employees may have been exposed to the substance.
CNN reported, citing Menlo Park Fire Marshal Jon Johnston, that no staffers were exposed to the substance.
Sarin is an extremely volatile nerve agent due to its ability to quickly evaporate from liquid to a gas. A person can be exposed to Sarin through skin contact, eye contact, or by breathing.