Three people are quarantined at the federal building on High Street in Hartford and the area is closed to traffic after white powder was reported in the mailroom.
Officials said the material was located around 12:40 p.m. at 135 High St.
Hartford firefighters, police, crews from the state Department of Energy and Environmental Protection and FBI are on the scene.
Three people and getting ready to be decontaminated.
Police said there is no threat to the external area. The substance is isolated and the neighborhood is safe.