Yesterday was the 21st year anniversary of the Tiananmen Square protests of 1989. Roughly 7,000 civilians were killed, according to NATO intelligence, after the government sent battle hardened troops to stop the protests. PLA military units originally from Beijing were sent away as they could not do the deed. They called in the 27th Army from Hangzhou to "clear" the protest area.
In this picture, special teams in full riot gear are visibly stationed in busy intersections near Tiananmen Square and downtown Beijing.