Thousands of rescue workers raked through debris in southwest China as Chinese premier Li Keqiang urged troops to leave no stone unturned and to “rescue every person” in the wake of a powerful earthquake that flattened villages and left more than 200 people dead or missing.

The 7.0-magnitude earthquake that has hit Sichuan province on Saturday killed at least 186 people, with many still feared pinned down under fallen houses as rescuers battled their way up mountain paths strewn with boulders to reach isolated villages.

More than 11,300 people were injured while 21 remain missing, the official Xinhua news agency said. At least 1,700 aftershocks have followed since the quake struck, Xinhua reported.

China’s new Premier Li Keqiang flew to Lushan county on Saturday to oversee efforts and said the first 24 hours was “the golden time for saving lives”.

Around 17,000 Chinese soldiers and police have joined the rescue mission and five drones were sent to capture aerial images, Xinhua reported.

However, roads leading to the disaster zone were clogged with traffic and massive debris, hampering further rescue operations. An aircraft was also sent to carry out rescue and relief work.

Japan has also extended a hand to its neighbor, saying it is “ready to offer maximum support,” Prime Minister Shinzo Abe said in a message to Chinese president Xi Jinping.

Saturday’s earthquake was a fearful reminder of the 2008 quake that shook Sichuan and left more than 90,000 people dead or missing.