Police investigating suspicious letter found outside Jan. 6 committee chair's office
Rep. Bennie Thompson / office of Rep. Bennie Thompson

U.S. Capitol Police are investigating a letter containing "concerning language" that was found outside the office of Rep. Bennie Thompson (D-MS), inside sources tell NBC News.

A statement put out by Capitol Police stated that nothing dangerous was found inside the letter, including any powder. "This afternoon Congressional staff inside the Rayburn House Office Building reported that they received a letter with concerning language. We just screened it and determined it not to have anything dangerous inside. Powder was not found inside," the statement said.

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"Our investigators take all concerning statements and threats seriously," the Capitol Police said in a post on Twitter. "They are now working to determine who sent the letter and why."

As NBC News points out, the incident comes two days before the Jan. 6 committee's next hearing, which was postponed due to Hurricane Ian.