This photo, released on Thursday, December 18, 2008, shows the staircase at a middle school in Chongqing, where the trampling accident occurred, resulting an injury of 25 students. [Photo: Chongqing Economic Times]

Twenty-five students were injured in a trampling accident at a middle school in southwest China's Chongqing Municipality on Tuesday.

The Chongqing Economic Times reported that the accident happened at noon when over 3,000 students were returning to their classrooms with their stools after a singing competition.

The students were swarming up onto a staircase and a squeezing panic occurred when some other fast runners who were already trying to squeeze down from the same stairs for lunch. Many students were trampled despite efforts by several teachers in trying to easy the tension.

Twenty-five students were injured, including five who were badly hurt.

The injured were immediately rushed to hospital and all of them were considered to be out of danger by Wednesday.

The accident is under investigation by the local education authorities.