CHONGQING, Aug. 18 (Xinhua) -- A bus that plunged from a bridge in southwest China's Chongqing Municipality on Monday evening killed four people and left 15 others injured, according to the local government.

    The bus collided with a van on a bridge in Wanzhou District at about 5:45 p.m. and then smashed through the railings. The four people died at the scene.

    The injured were taken to hospital immediately.

    A local work safety bureau official said poor operation procedures may have contributed to the accident.

    An investigation was underway.