From what I saw and heard live, I don't think it was staged, there were reporters broadcasting live via their phones from inside the room and initially thought what they heard sounded like a tray of dinner plates crashing to the floor as though a server had dropped a tray. At that point the people in room were not aware of what had happened outside the room. With that many people in a packed space, what could be heard could vary greatly from where you were sitting and it looked like a lot of people were unaware of any threat until the Secret Service stormed the room.

Reports were that Trump wanted to continue with the event which was completely stupid and the Secret Service overruled him.

The Secret Service and other law enforcement were heroes... it's a shame that law enforcement were not shown the same respect on and after Jan 6 when they defended the capital against a bunch of criminals who were pardoned by Trump.