A routine request in Florida for public records regarding the use of a surveillance tool known as stingray took an extraordinary turn recently when federal authorities seized the documents before police could release them, reports Wired.

The surprise move by the U.S. Marshals Service stunned the American Civil Liberties Union, which earlier this year filed the public records request with the Sarasota, Fla., Police Department for information detailing its use of the controversial surveillance tool.

The ACLU had an appointment last Tuesday to review documents pertaining to a case investigated by a Sarasota police detective. But marshals swooped in at the last minute to grab the records, claiming they belong to the U.S. Marshals Service and barring the police from releasing them.

ACLU staff attorney Nathan Freed Wessler called the move "truly extraordinary and beyond the worst transparency violations" the group has seen regarding documents detailing police use of the technology.