Prominent lawyer Zhou Ze revealed via twitter that he was shortly detained in Wenchuan, the site of Sichuan Earthquake.
Zhou was at the site of Yingxiu High School, where hundreds of students died in the quake, when some undercover police handcuffed him and dragged him away from because a Party leader would be visiting the same site. Zhou was released by the same group of police after the Party leader left about 10 minutes later. What's interesting from Zhou's description:
1) The 'leader' was a rather low level local official that according to posted policies does not warrant traffic control.
2) The undercover police's standard equipment includes a hand towel which is used to silence people from calling on the leader's attention.