Rescuers are working to save eight people left buried after a scaffold collapsed on a construction site in southwest China's Tibet Autonomous Region in the early hours of Monday.

They have already pulled out three workers who were trapped when building material and the scaffold fell on top of them in Bayi District of Nyingchi City, according to the regional publicity department.

The three workers have been sent to hospital along with two who were injured in the incident. None of their injuries are life-threatening.

It is not known if the eight still buried are alive or dead.

Top regional officials have ordered "all-out efforts" to rescue them and find out the cause of the accident as early as possible.

A subsidiary of China Railway Group is in charge of the construction project.