Rescue workers were searching for survivors on Wednesday as Japan counts the cost of the magnitude-7.1 earthquake that ⁠shook the south of the country, killing at least 13 people.Eight people were pulled from the rubble of a partially collapsed shopping centre near the city of Kumamoto torn apart by an apparent ⁠explosion about an hour after Tuesday's earthquake. Two of them – women in their 20s – were confirmed to be dead.The quake’s epicentre was about 20km south of Kumamoto, central Kyushu's largest city with a population of about 700,000. Power cuts were reported across the region after the tremor toppled factory chimneys, ruptured roads and bridges, and damaged a 17th century castle."Even now, there are people waiting to be rescued, and this is a race against time. We will marshal all available resources on the ground to save and rescue as ⁠many people as possible," Prime Minister Sanae Takaichi told reporters in Tokyo.About 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 southwestern island of Kyushu.Aeon shopping mall deathsJapan's TV Asahi said police confirmed that "several" people had died in the Aeon mall. Authorities are investigating a possible gas explosion at the site, Japanese media reported. Rescuers reported smelling ​gas inside the ⁠building, but the cause of the incident has not yet been confirmed, senior government spokesman Minoru Kihara said. Fire rescue teams, police and 170 military personnel were focusing on areas of the building where calls ​for help had been heard. More than 4,500 soldiers have been sent to help with recovery efforts.Earlier, NHK said that between 20 and 30 workers at the prefecture's largest shopping mall were unaccounted for after the mall was rocked by an explosion in the quake's aftermath.One side of the mall, which has about 200 stores, was torn away, exposing steel beams and strewing debris across a car park, footage showed. A mall representative said customers and employees were evacuated right after the initial earthquake and that the exact cause of the ensuing explosion was unclear. Authorities are investigating a possible gas explosion.Kazuya Tsurunaga told TBS he was stunned by the blast while cleaning up dishes broken by the earthquake inside a pub about 300 metres 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."Chimney of paper mill topples overMultiple people were also unaccounted for after a chimney collapsed at a Nippon Paper Industries factory, broadcaster NHK reported, while two hospitals were each said to be treating more than 50 people, some in serious condition.An aerial view shows a collapsed chimney at Nippon Paper Industries' Yatsushiro Mill. Kyodo / via ReutersInfoThere were no irregularities reported at nuclear power stations ​in the area, Japan's nuclear regulator said. Companies including Sony and TSMC, the world's largest contract chipmaker, have plants in the quake area. A Sony representative said the company was checking ​the situation. ⁠TSMC said all personnel at its Japan site were confirmed safe and operations ‌were gradually resuming.A tsunami warning was ⁠issued immediately after Tuesday's quake, but was later lifted.Bridges and buildings collapseAuthorities said they were responding to multiple incidents where buildings had partially collapsed or caught fire. One person died in one such collapse in a town near the epicentre.The Kyushu motorway was damaged in both directions. Kyodo / via ReutersInfoSome roads were also badly damaged, with large cracks splintering major highways, snarling traffic. Rail services were suspended and flights were grounded.Several passengers on high-speed trains at the time of the quake were also injured, operators said. Authorities immediately suspended all services after the disaster.Homes on fire in Yatsushiro, Kumamoto prefecture. Kyodo / via ReutersInfoKumamoto Castle walls fallA ⁠massive earthquake in Kumamoto ​10 years ago killed 275 people and injured ​a ‌further 2,739, according to an official count.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.The collapsed stone walls of Kumamoto Castle. AFPInfoAuthorities have warned residents in the areas that felt the biggest tremors to be on alert for further strong quakes for about a week. There is also a risk of landslides, officials said.With more than 36,000 homes still without power as temperatures soared to about 34°C on Wednesday, authorities also warned about the risk of heatstroke.Japan is one of the world's most earthquake-prone countries, with a tremor occurring at least every five minutes. Located along the Ring of Fire, a series of volcanoes and oceanic trenches that partly encircle the Pacific Basin, the East Asian country accounts for about 20 per cent ​of the world's earthquakes with ‌estimated magnitudes of at least 6.0.