From CBC News:
The U.S. embassy in Beijing has warned Americans to be wary of a “possible terrorist threat” when travelling in China.
The warning was distributed to Americans in China through a warden notice that was published on the embassy’s website on Friday, by e-mail and by telephone.
In the notice, embassy officials said they had received “unconfirmed information of a possible terrorist threat” in the major cities of Beijing, Shanghai and Guangzhou. “This threat also may exist for places where Americans are known to congregate or visit, including clubs, restaurants, places of worship, schools or outdoor recreation events.”[full text]