(CNN) -  

A worker at the federal courthouse in Birmingham, Ala., shot himself in the head Thursday, the U.S. Marshals Service said.

The man walked into the chief clerk's office at the Hugo Black U.S. Federal Courthouse "mumbling about a will. He then put a gun to his head and pulled the trigger," CNN affiliate WBMA reported, citing a source inside the courthouse. The FBI confirmed the source's report, WBMA said.

The man, described only as a "middle-aged white male," was taken to a hospital. His condition was unknown, the agency said.

There was no threat to the courthouse, the agency said.

Birmingham police are investigating, the marshals service said.