The steel plate was found near the Post’s headquarters and the office of Washington Post Co., which owns the paper, on Friday, the company said.
The steel was taken to the FBI for analysis, according to a statement.
The plate was used to keep an air gap in the building during the 2012 terrorist attacks on the U.S. Capitol, according the company.
“The plates were found on a floor of the Washington Times building, which is an essential floor area for the newspaper and a large office building, said a spokesman, David Johnson.
The company said it will not disclose the number of times the plate was in use. “
We believe this plate is not related to any recent attacks,” the company added.
The company said it will not disclose the number of times the plate was in use.
It is unclear how many times the plates were used.
Washington Post spokeswoman Rachel LaCapria declined to comment.
The plates were recovered on Friday at the top of a steel plate that covered the newsroom, Johnson said.
“We are investigating this incident and are cooperating fully with the FBI,” he said.