Overall, 13 people were killed, five were in cardiac arrest and at least eight others seriously injured, authorities said. Authorities are investigating a possible gas explosion at the Aeon mall. "I thought a bomb had gone off," Takateru Sonoda, 41, who runs a combined hair salon and cafe near the mall, told ‌Jiji Press. The quake's epicentre was about 20km south of Kumamoto City, central Kyushu's largest city with a population of about 700,000. Public attention was focused on the collapse of the Aeon shopping centre, the largest ‌in the prefecture.