At least nine people have died and more than 250 are injured after a powerful earthquake hit southern Japan, toppling buildings and cutting power supplies, the BBC reports.

Officials say more people could be trapped under collapsed buildings.

Thousands fled their homes and many people spent the night in the open in the town of Mashiki, near Kumamoto city on the island of Kyushu.

Troops have been sent to the scene but rescue operations are being disrupted by aftershocks, officials said.

No tsunami warning was issued after the magnitude 6.4 quake struck at 21:26 on Thursday (12:26 GMT) east of Kumamoto.

Nuclear reactors on the island are not reported to have been affected.

The two Sendai nuclear reactors on Kyushu were operating as normal while the three Genkai nuclear reactors still in operation were already closed for routine inspection.