The FBI hasn't been able to confirm the presence of a white powder that an employee at the federal courthouse in St. Paul reported seeing after opening a pile of mail.
Authorities said a court employee opened some mail in the courthouse mail room on Monday afternoon and noticed a short time later that the package had left a white, powdery residue on her hands.
The U.S. Marshal's Service started evacuating the building and three court employees were taken to nearby Region's Hospital as a precaution. St. Paul police also responded to the incident, and the St. Paul Fire Department sent a hazardous materials team.
FBI Special Agent Steve Warfield says the bureau took several items from the scene to a crime lab, which wasn't able to find the powder the employee reported seeing.
Warfield says agents were also unable to find any threatening communications when the searched the courthouse on Monday.
The courthouse was open on Tuesday morning.
(The Associated Press contributed to this report.)