At least 12 people were killed after a powerful 7.3-magnitude earthquake rattled Kumamoto Prefecture in Japan’s southwestern Kyushu island early Saturday, bringing the death toll to 21 since another temblor jolted the same region late Thursday.

The Japan Meteorological Agency (JMA) confirmed that the quake, which struck Thursday night and was measured at 6.5 magnitude, was the foreshock of the Saturday’s disaster, warning that there might be more aftershocks in the coming days, reports Xinhua.

Japanese Prime Minister Shinzo Abe cancelled his planned visit to Mashiki town, the epicentre of the quakes, scheduled for Saturday.

Many houses and buildings in the small town, which were already damaged during the devastating foreshock, were totally ruined by the 7.3-magnitude quake on Saturday, forcing people to take shelters in public facilities that also offer food and water supply.

‘It was my first time in about 70 years to experience such huge earthquake,’ Yoshimura, who lives in Mashiki, told Xinhua, adding that he slept only one hour in the two days. The old man was staying in an earthquake shelter early Saturday as his house was severely damaged.

He also expressed his worries over the operating Sendai nuclear power plant near the quake-rattled Kumamoto Prefecture.

Since a massive quake-triggered tsunami pummelled the Daiichi nuclear power facility in northeastern Fukushima Prefecture in March 2011, an increasing number of Japanese have opposed the government’s plan to restart the stalled nuclear plants due to country’s pro-quake location.

However, no abnormalities were observed at the Sendai power plant, said local officials.

The epicentre of Saturday’s quake is located at Aso city in Kumamoto Prefecture and logged at level of upper 6 in the Japanese seismic intensity of 7. As of 12:00 local time, about 80 aftershocks occurred with some measured around 6 magnitude.

Travelers in a resort hotel rushed out of the building after the powerful quake struck at around 1:25am local time (1625 GMT Friday) with some in their pajamas.

Things fell down from walls and beds and furniture were shaken badly. Windows, elevators and water pipes were destroyed in the hotel which survived the major quakes on Thursday and Saturday.

The main expressway from Aso to Kumamoto city was closed due to deep cracks in the road. Parts of the highway in the prefecture and the Kumamoto airport also shut down.

In Minamiaso village, the main road to the village was blocked by landslides and the city office building in Uto reportedly collapsed. Convenient stores and restaurants in the area were closed with items falling off shelves.

A small-scale eruption was recorded at Mount Aso in the prefecture at around 8:30 am but the JMA said it was not clear whether the eruption was linked to the temblors, according to Japan’s Kyodo News.

The weather agency also warned that torrential rains were expected in the quake-affected areas, which might trigger massive landslides.

Some 68,900 people were staying at 655 shelters, said the Kumamoto prefectural government and 1,500 were injured in the latest quakes.

The Defence Ministry said that it will dispatched up to 15,000 Self-Defence Forces members to Kumamoto for search and rescue operations on Saturday and 5,000 more on Sunday to assist teams already on the ground.