I don't know. How many?
What people seem to miss is that senator’s are affected the same security as POTUS while in the capital building. They all have protective service details and are guarded with ROE of deadly force is not only authorised it is mandatory should the primary under protection be in danger. There was a barricaded doorway behind which were PSD protected clients that was the last line of defence and a clear barrier to entry breaching that barrier was not only a felony it also was a direct act of aggression towards the primary. If POTUS was behind that door with his SS protective team would you have expected them not to shoot the first person through the breach with a angry mob on the other side of the door?
Answer that question directly if POTUS at the time Donald had been behind that barricaded door and a mob of shouting angry people was on the other side would you have expected his SS detail to not fire on the first person who battered their way through a barricaded and barred door. Every PSD team in the world would have and should have reacted the same way you fire on the first person through the breach to stop the momentum of the crowd period.
I have done PSD duty as the PSO for the U.S. Military and Fed Gov I would have opened up with automatic weapons fire on the first person to breach my inner and last cordon while actively protecting my primary from a mob threat as I would have expected any member of my PSD team to do the same. There is a reason the officer was not charged he did the text book response to an active threat in a barricaded situation and a high value primary. That’s the facts while unpleasant for some to admit it doesn’t change the rules and laws while protecting high value personnel during a declared riot or other period of active civil unrest.