Three high-ranking U.S. Marshals Service officials based in the District have been placed on administrative leave pending an investigation on allegations of “serious misconduct,” officials said Thursday.

Dave Oney, a public affairs specialist with the U.S. Marshals Service, said that the chief deputy U.S. Marshal and two assistant chief deputies assigned to the H. Carl Moultrie I D.C. Superior Courthouse are facing an internal investigation. The names of the three officials have not been released.

Due to the serious nature of the investigation, the Department of Justice Inspector General’s office is assisting in the case, Oney said. He said it was not clear what misdeeds may have occurred. He also said that investigations on such a scale are rare.

The U.S. Marshal Service, a federal law enforcement agency, operates in 94 federal judicial districts and employs about 4,000 deputy U.S. marshals and criminal investigators.