Chinese Censorship

I met a man who told me an interesting anecdote. On a recent trip to China he had been visiting Tiananmen Square. Their Chinese guide, ex-army, recognised about thirty people in the square as plain clothed policemen, due to their searching eyes and directionless wandering. Then suddenly a man threw up a bundle of leaflets into the air, scattering them to the wind. About twenty of the up until that point incognito policemen bundled on top of the man to restrain him, whilst the other ten hurriedly collected the leaflets. Their Chinese guide strongly advised him not to take any photographs of the scene. What did these leaflets say? Did they specifically talk about the Tiananmen Square massacre that Chinese authorities now deny ever happened, or just a general indictment of the dictatorial government regimes crimes against people and humanity? Altogether scary stuff, and a reminder that despite the diplomatic niceties of Western nations, China is still in the stranglehold of an authoritarian dictatorship.