Damage is seen to part of the compound of the Shohinken gardens in Yatsushiro, Kumamoto Prefecture, July 29, after an earthquake struck the area the day before. AFP-Yonhap

YATSUSHIRO, Japan — Rescuers frantically searched for survivors on Wednesday, a day after a 7.1-magnitude earthquake shook southern Japan, killing at least 13 people, knocking out power to thousands of homes and rupturing roads across the region.

Eight people were pulled from the rubble of a partially collapsed shopping mall near the city of Kumamoto that was torn apart by an explosion about an hour after Tuesday's earthquake. Of them, three have died.

Mall operator Aeon said four workers at the Kumamoto shopping centre remained unaccounted for after checks of the roughly 2,700 staff. Customers had been evacuated right after the initial quake.

"Even now, there are people waiting to be rescued, and this is a race against time," Prime Minister Sanae Takaichi told reporters in Tokyo. "We will marshal all available resources on the ground to save and rescue as many people as possible."