Beijing, Eleven of the 29 people trapped on Friday in a collapsed gypsum mine in east China have been rescued by Saturday morning, rescuers said.

Rescuers lifted a trapped miner, whose leg was stuck under a boulder, from the mine early Saturday morning after hours of hard work, Xinhua reported.

At least 29 people were working in the shaft when the mine collapsed around 7.56 a.m. (local time) at the gypsum in Pingyi county.

Rescuers have located the 18 miners who are trapped at two different sites. However, continuous deformation of the tunnel and falling rocks are hindering rescue efforts, experts of the rescue team said.

The cause of the collapse is still under investigation.

According to the official microblog of China Earthquake Networks Center, the collapse caused an earthquake measuring four on the Richter scale in Pingyi County.

The shock affected local rail service, with 10 freight trains halted and eight passenger trains delayed on Friday morning. All trains had resumed service as of noon on Friday, the Jinan Railway Bureau said.