A bus accident on a highway in southwest China's Yunnan province on Tuesday has left eight people dead and one seriously injured, according to police.

The bus, carrying 33 passengers, tumbled into a ditch along the highway in Jianshui county in Honghe Hani and Yi autonomous prefecture at 1:15 p.m., police told Xinhua.

The driver, Bai Xingcheng, 48, male, and another four passengers died at the scene. Three others died after being sent to hospital while one has been confirmed to be seriously injured.

The highway, after a period of closure, reopened to traffic at 5:10 p.m. and investigation into the cause of the accident is under way, police said.