Rescuers were informed that 21 workers were trapped after a 30-metre long section of the expressway tunnel in Longyan City collapsed.
Debris, estimated at 5,000 cubic metres, have blocked the tunnel which was being expanded to accommodate the expressway linking Xiamen City of Fujian and Chengdu, capital of country's southwest Sichuan Province, state-run Xinhua news agency reported.
A search operation was under way. There was no immediate information on the casualties.