8-1 Police presence, and recent Nanchang protest

I went to a market today and my bus passed by 8-1 Square (八一广场) where I met a surprising (to me) sight. Military—not carrying weapons, from what I could see—and police officers were stationed at all the entrances to the monument presumably to prevent people from gaining access to the monument — the main attraction of the square. Nothing was happening and everyone was standing around purposefully. I have no idea why.
Today’s experience made even more shocking the news that a few days ago 10,000 students may have demonstrated and torched buildings and the luxury cars of their officials. I haven’t heard anything about this until tonight. Please note that my host school, Nanchang University (南昌大学), is not mentioned in any of the reports I’ve read online.