A HAZMAT (hazardous materials) team has been scrambled to the Federal Building in downtown Minneapolis.
The Minneapolis Fire Department says the alarm was raised because of a "white powdery substance" found by an employee "when they opened a mailed in application."
"HAZMAT Team made entry and is working to identify substance," the fire department tweeted, noting that the Minneapolis Police Department bomb squad is also on the scene.
The Federal Building at 212 3rd Ave. S was constructed for use as a post office in 1913 but has been used for federal services since the 1930s.
Its website says it houses offices for the Department of State-Passport, HUD, Housing and Urban Development and the National Labor Relations Board.