Multiple people were feared dead when a 7.1-magnitude earthquake hit Japan's southern Kumamoto prefecture Tuesday.

The quake also knocked out power to thousands ⁠of homes, rupturing roads and leaving some trapped inside a partially collapsed shopping mall.

Speaking to reporters 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, and hundreds of soldiers have been deployed to help with rescue operations as aftershocks continued to rumble in the area, on Japan's southern island of Kyushu.

Multiple people were unaccounted for after a chimney collapsed at a Nippon Paper Industries factory, broadcaster NHK reported.

'Like volcanic ash falling'

Around 20 to 30 workers at the prefecture's largest shopping mall were unaccounted for after it was rocked by an explosion in the aftermath of the quake, NHK said.

Fire services earlier said multiple people were trapped inside, while police said "quite a few" were presumed dead in the incident, broadcaster TBS reported.

One side of the mall, which houses around 200 stores, was torn away, exposing steel beams and strewing debris across a vast parking lot, footage showed. Several ambulances and fire engines were parked outside, as rescue teams searched for survivors.

A spokesperson for mall operator Aeon said customers and employees were evacuated right after the initial quake and ⁠that ⁠the exact cause of the ensuing explosion was unclear.

Kazuya Tsurunaga told TBS he heard the explosion while cleaning up dishes broken by the earthquake inside a pub about 300 meters from the Aeon mall.

"It was a huge impact," he said. "A large cloud of smoke billowed up, and because the wind happened to be blowing and the wind direction was towards the shop, the area around us was in a state like volcanic ash was falling."

One hospital reported more than 50 injuries, and another around 40, including 10 in a serious condition, public broadcaster NHK said. Several people on a high-speed train at the time of the quake were also injured, media reported.

Buildings on fire

Several other buildings were also on fire or partially collapsed, according to footage from NHK, while large cracks appeared on major roads, including an elevated highway. Rail services were halted and flights grounded.

TSMC, the world's largest contract ⁠chipmaker, Sony and Fujifilm evacuated workers from their plants following the quake.

Tokyo Electron, another major chipmaker, said it was suspending operations at its two factories in Kumamoto through Wednesday, while Honda said it would also temporarily idle its motorcycle factory there.

The quake’s epicenter was about 20 kilometers (12 miles) south of Kumamoto city, central Kyushu's largest city with a population of around 700,000.

Residents in ​the areas that felt the biggest tremors must beware of further strong quakes for about a week, as well as the risk of landslides, an official ​for the Japan Meteorological Agency said.

Tsunami warning lifted

Located along the "Ring of Fire" of volcanoes and oceanic trenches partly encircling the Pacific Basin, Japan accounts for about 20% of the world's earthquakes of magnitude 6.0 or more.

A tsunami warning was issued immediately after Tuesday's quake, but was later lifted.

Kyushu ⁠Electric Power said 48,000 ‌homes had ‌lost power as a result of the latest quake, while railway company JR Kyushu said that it had suspended ⁠services, including its high-speed bullet trains. Kumamoto airport also shut its runway, as airlines diverted and ‌cancelled flights.

Telecoms operators KDDI and Docomo said there was disruption to their mobile phone services due to power shortages and transmission-line failures.

There were no irregularities reported at the nuclear power stations in the area, ​Japan's nuclear regulation authority said.

A massive earthquake in ⁠Kumamoto 10 years ago killed 275 people and injured a further 2,739, according to an official count, and damaged ⁠thousands of buildings including the city's castle, a top tourist site.

Some portions of the stone walls at the castle also collapsed as a result of Tuesday's ⁠quake, an official at the castle's office ​said.

With thousands of homes still without power as night fell, authorities warned residents about the risk of heatstroke as temperatures were set to hit 34 degrees Celsius (93 degrees Fahrenheit) on Wednesday.