> How were they planning on taking hostages without guns?

Don't be obtuse. Had members of Congress not evacuated their chambers just the fact a mob was outside the doors would be holding them hostage. Several rioters had flexi-cuffs and other bindings. It's not terribly difficult to hold someone hostage. It's downright easy for a large group of people to imprison a smaller group, especially one composed of unarmed geriatrics.

> Were they going to beat people with flagpoles?

You've got from obtuse to insipid. The answer is yes. They literally beat people with flag poles. Several were armed with guns. Many were armed with other blunt weapons, stolen police weapons, and chemical sprays.