BOSTON (CBS) -- Officials say a couple workers got a bit of a scare on Monday after an unknown powdery substance was found on the second floor of the federal courthouse in Boston on Monday.

Police were called to the scene around 3:30 p.m. after workers found a white substance in an envelope.

Fire officials say a hazmat team was then called in. They checked the envelope and no hazardous readings were detected.

The substance will be analyzed at a state medical lab in Jamaica Plain.

The incident remains under investigation.

No additional information was immediately available.