A 7.1-magnitude earthquake hit Japan's southern ​Kumamoto prefecture on Tuesday, knocking out power to thousands of homes, rupturing roads and leaving some trapped and others presumed dead inside a partially ‌collapsed shopping mall.

Speaking to reporters at her office in Tokyo, Japanese Prime Minister Sanae Takaichi said authorities were still assessing the full extent of the damage in the area, which was devastated by a deadly quake a decade ago.

"We have already been informed that people have been injured. Power outages and fires have occurred in some areas, and there has also been damage to roads and bridges and the ​collapse of buildings," Takaichi said.

"I ask everyone to take action to protect themselves, including evacuating to a safe location."

Around 300,000 people have been instructed to go ​to evacuation centres, the disaster management agency said, while Takaichi said 3,600 soldiers would be deployed to help with the disaster recovery ⁠as aftershocks continued to rumble.