KUNMING, Feb. 20 (Xinhua) -- Police in southwest China's Yunnan province have detained a driver in connection with a road accident that killed nine people and injured 24 on Saturday, local authorities said Monday.

A vehicle carrying 37 passengers overturned on an expressway in Nanhua county at 11:25 p.m. Saturday while en route to the city of Dali, according to a statement by the local government of the Chuxiong Yi autonomous prefecture.

An investigation into the cause of the accident is under way, Chuxiong police said, adding that the driver is also being investigated for his role in the accident.

All the injured are receiving treatment at local hospitals.