A group of Shanghai residents who had applied to the government for the right to hold an anti-maglev protest were rejected by the government. Despite this, small numbers of them intended to go on another "walk" in order to publicly air their grievances. This time, they were stopped by some other residents. According to this AP article, this is what happened:

Residents in armbands used a megaphone to warn people not to "linger here too long," to avoid problems with the police, who had rejected their petition to hold a protest march against the magnetic levitation, or maglev, train.