Emergency crews were called to the tax office in Hartford after a suspicious white substance was found inside an envelope.
Hartford Deputy Fire Chief Raul Ortiz said the substance was found in an envelope in a mail room.
The Department of Energy and Environmental Protection responded, along with the Capital Region Hazmat. The FBI responded as well, and will lead the investigation.
Three people were quarantined, Ortiz said, however no injuries were reported.
The first floor and the mail room were evacuated.
Hartford police said samples of the substance were collected for further analysis.
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