A total of 12 people were killed and 10 others injured following a tunnel incident in southwest China's Yunnan Province as local official declared end to the search operation on Wednesday afternoon.

All the injured, including four in critical conditions, are being treated at hospitals, the government said. 

The incident on November 26 saw a sudden water and mud burst at a tunnel exit on a highway in Fengqing County, Lincang City, which was followed by a second burst shortly after within an hour.

According to local government statement, the bursts have affected an area of round 15,000 cubic meters with a flow of 800 cubic meters per hour, causing sudden blockage of part of the tunnel, toppling equipment and trapping people.

The tunnel was under construction during the time and all the victims were workers on site.

A probe is underway.

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Six killed, six missing after highway tunnel collapses in SW China