The FBI speculates possible armed protests all around the 50 US state capitals after the decision.
President Donald Trump has officially been impeached for the second time with 232-197 votes.
The step that was taken by Democrats, supported by 10 Republicans will have its official trial after Joe Biden takes charge as the US president next week.
The decision was taken by the Democratic-controlled House on Wednesday while the National Guard troops kept a watch outside Capitol.
The FBI speculates possible armed protests all around the 50 US state capitals after the decision of impeachment.
Donald Trump's incitment of the Capitol Hill riots has made him the first president in US history to be impeached twice.