We really don’t know. The first time I heard about this was when I was in middle school and just after the history class, one of my classmate dragged me to the corner and he was like “wanna know something bad”? And then he told me that Deng had the army set up machine guns at the square and starts shooting people, ofc he didn’t mentioned when and why or any details. I didn’t believe him back then. The old generation know more or less about it but they dont talk about it. One of my friend’s father was there in person. He also never said anything about the incident.
Most people have no idea what happened, even if they do, there is very little chance they have any clues about the details. They know that there was some kinda riot but that’s it.