If you watch and read the links I provided earlier, it is clearly stated that they were plain clothes security police.
Security police, to this day, beat people dead for lessor actions. Never use wiki when far better sources are available for the clicking!
The Chinese have a whole mechanized army (literally) that are all security police; they were massed outside of Hong Kong and were the first in when it fell.
64memo.com
They did not fair well.