I arrived just before noon, and wrote down events and times as I saw them. I'm only going to report what I had written here and spare artistic license for when I can collect my thoughts.
@~12:20pm we reached about 100-200 people, the critical mass which held for several hours.
From 11:30 - 2:20 the law enforcement presence was ~15 Federal Protective Service(FPS), 2 of which patrolled the courtyard and 5 more walked around the entrance above the stairs. There were ~10 SPD bike cops, and US Marshals who stayed inside the building.