Hello Darth,
Most of them thought they were just going down to the capitol to protest outside. And that's what most of the crowd did. But not all. The worst extremist right wing trouble makers had violence on their minds and in their plans. They picked up right where Trump the inciter left off and urged the crowd forward, past the barriers, past the police line, upward, higher, up the steps, smashing windows, going in disrupting the government, trying to prevent the election certification, trying to force their way upon the legal and fair election to force a continuation of the presidency of Trump, even after he had been voted out.
When a small minority crowd tries to take over our government by force, that is called an insurrection.