The U.S. Capitol Police said that it learned of a possible threat against members of Congress and the Capitol complex by “an identified militia group.”

“The United States Capitol Police Department is aware of and prepared for any potential threats towards members of Congress or towards the Capitol complex,” said a news release from the agency on Wednesday, adding that there is a ” possible plot to breach the Capitol by an identified militia group on Thursday.”

The release added: “We have already made significant security upgrades to include establishing a physical structure and increasing manpower to ensure the protection of Congress, the public, and our police officers.”

The department did not elaborate on the nature of the threat or provide details on the alleged militia group. The FBI and Department of Justice have identified some individuals who were arrested after the Jan. 6 Capitol breach as members of militias.

So far, more than 300 people have been arrested in connection to the Capitol breach, said FBI Director Christopher Wray in a Senate hearing. Wray also stated that the FBI is viewing the breach as a “domestic terror” incident.

“Due to the sensitive nature of this information we cannot provide additional details at this time,” the release stated, adding that it is taking the received intelligence seriously.

The department added that it is working to gather intelligence with federal, state, and local law enforcement agencies.

The announcement comes days after the Capitol Police Department stated on Twitter that it has taken steps to increase security around the Capitol. Inauguration Day used to be March 4 under the U.S. Constitution, until the passage of the 20th Amendment in 1933, which moved the date to Jan. 20. Claims have been circulating on social media platforms suggesting that former President Donald Trump would return as the president on Thursday to reclaim power.

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