JINAN, Oct. 21 -- Two miners have been rescued and 18 more remain trapped after a rock burst at a coal mine in east China's Shandong Province, local authorities said Sunday.

The accident happened at around 11 p.m. Saturday at Longyun Coal Mining Co. Ltd. in Yuncheng County. A total of 22 people were trapped following the rock burst.

More than 170 rescuers, including medical workers and firefighters have been dispatched to rescue the injured and search for the trapped miners. The two miners who were rescued Sunday afternoon have been hospitalized.

Another two other miners have been confirmed dead.

The rest are now trapped in a tunnel, which has been blocked by falling coal seam at the two ends, according to Pan Zhongmin, an official of the company, adding that rescuers are clearing the obstruction to reach the trapped.

The cause of the accident is being investigated.

Rock burst accidents are often caused by fractures in rocks due to mining.