From what I heard the crowds were waiting for a second Trump speech in front of the capital but it turned out to be misinformation , then the instigators removed the fence and started crowd controlling people to walk up the stairs. Most were already starting to go home at that point. ANTIFA then were let in and agitating .for the cameras.They had fake news reporters reporting at the front to make it look like it was a riot. The thing is many people weren't able to upload and stream or make calls and but these fake news reporters could. They also had to censor Trumps twitter and anyone else trying to report what was really going on so only the one narrative would come out saying Trump supporters rioted like hooligans. These are the same tactics they used in previous color revolutions to instigate a civil war.
I heard from someone who was there, everyone thought there was a second speech in front of the capital, 100k started gathering in front of the capital and people were coming with their kids. But there actually wasn't a speech. Antifa then removed the fences in front got crowds to go up the stairs then attacked the capital themselves to make it look like it was being attacked by Trump supporters. Most of the crowd were already leaving at that point because no speech. It was a set up.