CHICAGO (CBS) — Workers at the Dirksen Federal Building mailroom came in contact with a substance in a package they deemed suspicious on Wednesday.

Chicago Police and Fire responded and found nothing hazardous and the employees were simply told to wash their hands.

The mailroom is on the 20th floor and the building on South Dearborn Street in the Loop  is home to the U.S. attorney’s office for Chicago.

The FBI is aware of the report and is investigating with the Chicago Fire Department.