When asked for parallels in US history,
the r/AskHistorians folks had to reach for things like the pogrom against the black population of Wilmington, NC and gunpoint removal of its government by a Red Shirt mob in 1898. They could not find anything in the 20th century US. Its also worth saying that this happened simultaneously in many different states and territories although the events at the Capitol got the most attention.
For the timidity and stupidity of our enemies may we be truly thankful. Political violence is
a strong tradition in the United States. But I do not know if the United States can go anywhere good from here. The killing did not stop after Tiberius Gracchus' body was hauled out of the Forum.
Edit: To be tactical and journalistic (thinking about the next two weeks not two decades) the resignation of several US cabinet ministers makes it less likely that a majority will invoke section 4 of the
25th amendment. I think that cabinet ministers are the "the principal officers of the executive departments" in the text of the amendment.
Edit: The gang with the beards, the bullet-resistant helmets, the black tactical gear and the bundles of temporary handcuffs look like someone I knew in Alberta. Jordan Guy MacDonald Goudreau, the wannabe conquerer of Venuzuela last May, was from Calgary.
Edit: I am also seeing allegations that at least six state legislators were in the mob which stormed the Capitol
If you are new to this world, David Neiwert, who has been studying the radical right in the United States for 20 or 30 years, has a new book
Red Pill, Blue Pill: How to Counteract the Conspiracy Theories That Are Killing Us (Prometheus, 2020)
Amazon.