Fire officials responded to Facebook's Menlo Park facility after a packaged delivered to the location tested positive for sarin.
Continue Reading Below
The bag tested positive for sarin, a deadly nerve agent which has been used in chemical warfare, while going through a machine in the mailroom.
Fire officials in Menlo Park, California, which is part of Silicon Valley, said the staff was evacuated and the bag was quarantined.
They said no one was showing any signs of symptoms from the toxic chemical, and it is yet unclear if there is an actual threat or a false positive.
"At 11:00 AM PDT this morning, a package delivered to one of our mailrooms was deemed suspicious. We evacuated four buildings and are conducting a thorough investigation in coordination with local authorities," Anthony Harrison, Facebook spokesperson, said in a statement to Fox News.
"Authorities have not yet identified the substance found. As of now, three of the evacuated buildings have been cleared for repopulation. The safety of our employees is our top priority and we will share additional information when it is available.”
"Sarin is a clear, colorless, and tasteless liquid that has no odor in its pure form. However, sarin can evaporate into a vapor (gas) and spread into the environment," according to the Centers for Disease Control and Prevention.
Exposure to large doses of sarin can lead to symptoms including loss of consciousness, convulsions, paralysis and respiratory failure possibly leading to death, according to the CDC's website.