The major hazmat response and drama Monday in Menlo Park was allegedly much ado about nothing, but what would cause a screening machine to come back with a positive test for sarin?

Perhaps it was machine error, and after a 14-hour ordeal that temporarily shut down a portion of Facebook's campus, the company issued a statement early Tuesday saying that the package had come back negative for sarin in final tests, and no employees were exposed to any of the toxin.

The package first arrived at 11 a.m. Monday. As ABC 7 reports, an "open-air test" following the machine's positive test actually came back negative, but the hazmat response was apparently necessary in order to thorough dissect the package. Early reports suggested there had been two positive tests, and one negative.

The scare led to the initial evacuation of four buildings including the company's mail-sorting facility on Hamilton Court, just south of Facebook's main office buildings along the Bay. Only the mail building remained evacuated for most of Monday.

Via the LA Times we have a statement from the FBI saying that law-enforcement labs “thoroughly tested the items in question and determined them to be nonhazardous.”

Facebook's director of corporate media relations Anthony Harrison issued a statement as well telling Variety, "Authorities have confirmed test results were negative for any potentially dangerous substance and the buildings have been cleared for repopulation." Harrison added, "Our rigorous security and safety procedures worked as intended to limit exposure and keep our people safe."

The incident highlights how extraordinarily cautious Facebook is these days with its mail.

Previously: Facebook Evacuates Several Buildings After Possible Sarin Gas Exposure In Menlo Park