KUNMING - Eight people were killed and many others injured when a passenger bus overturned in Southwest China's Yunnan province on Friday morning, local authorities said.

The accident happened at 10:50 am on a section of the Chuxiong-Dali Expressway in Nanhua county in Chuxiong Yi autonomous prefecture when the bus veered off the expressway and rolled down a 20 meter hill, according to the prefecture's publicity office.

The injured are being treated in a local hospital though the exact number is not immediately available.

An investigation into the cause of the accident is under way.