[cortesoft]

I think they would have been able to arrest everyone inside the Capitol building, since everyone inside was breaking the law.

[pvarangot]

Yes most definitely. They also have the infrastructure to do so, but not sure they have the infrastructure to keep them arrested until everything is sorted out.

[vkou]

They absolutely have that infrastructure. Handcuff all of them, and let them lie face-down on the pavement while you process them.

That's what usually happens with mass arrests.