Japan's south-western Kyushu region has had more than 100 aftershocks since it was struck on Tuesday by a powerful earthquake which left at least 13 people dead. In searing heat, rescue crews are digging through the rubble at a paper factory and a shopping mall in Kumamoto prefecture, looking for trapped survivors. Japanese Prime Minister Sanae Takaichi warned it was "truly a race against time" to rescue those trapped. The Japan Meteorological Agency (JMA) is urging residents to be alert for the possibility of strong aftershocks, public broadcaster NHK reported. Tuesday's quake hit the Kumamoto prefecture on Kyushu island at 16:27 local time (07:27 GMT).