The number of people who have died after a powerful earthquake hit southwestern Japan has risen to 28, authorities said on Thursday

Rescuers are still working to find survivors after the magnitude 6.8 earthquake hit Kumamoto prefecture on Kyushu island on Tuesday, causing widespread damage to houses and power lines. BBC reported.

Several people died after part of a shopping centre collapsed and an explosion ripped through the mall about an hour later.

Thousands of displaced residents are now staying in evacuation centres - though the challenge is to keep them cool and hydrated as the region battles sweltering heat.

Temperatures could reach 39C in the prefecture in the coming days, according to forecasts, with officials urging survivors and rescuers to take precautions against heatstroke.

On Wednesday, Japan's defence minister Shinjiro Koizumi announced the delivery of 300 air conditioners to Kumamoto, with 150 of the units bound for evacuation centres.