Facebook Inc evacuated four buildings on Monday after a package at the social media company’s Silicon Valley mail facility tested positive for the nerve agent sarin.

Iran Press/America:Two people were also evaluated for possible exposure to the the toxic compound.

The people who came in contact with the suspicious package at about 11 a.m. did not show any symptoms of exposure to sarin, said Jon Johnson, fire marshall for the city of Menlo Park, where Facebook is based, Reuters reported.

“The (Facebook) facility tests all of the packages that come in and they had a positive test, so they just initiated their standard protocol. Now we’re just waiting to verify whether that’s true or not,” he said.

Facebook spokesman Anthony Harrison said the company evacuated four buildings following the positive test and was cooperating with police in the investigation.

“Authorities have not yet identified the substance found. As of now, three of the evacuated buildings have been cleared for repopulation,” Harrison said.

Agents from the San Francisco office of the Federal Bureau of Investigation were responding to the scene, a spokesman for the agency said.

Sarin, a potent toxic compound that disrupts the nervous system, has been used as a chemical weapon. Exposure can be fatal.

Meanwhile, New York Governor Andrew Cuomo on Monday ordered the U.S. Department of Financial Services to investigate reports that state-regulated advertisers were using Facebook Inc’s advertising platform in a discriminatory manner.

This is the second investigation that the state governor has ordered into the social media company this year.

In February, Cuomo ordered two state agencies to investigate a report that Facebook may be accessing far more personal information from smartphone users, including health and other sensitive data, than had previously been known. 213/