The Santa Clara County fire department arrived at Apple’s Building 4 on De Anza Boulevard at about 3:30 p.m. Wednesday dressed in hazmat gear after they were called to the scene following the discovery of a suspicious envelope, reports the San Jose Mercury News.

An employee reportedly found the envelope, which contained an unknown white powder, in the Apple cafeteria. Preliminary test turned up no signs that the substance was hazardous but it was taken to a Santa Clara County lab for further evaluation.