A powerful earthquake has struck southern Japan, killing at least two people and injuring hundreds of others.

The quake hit at 9.26 pm and was centered seven miles east from the town of Mashiki in the Kumamoto prefecture, according to Japan's Meteorological Agency,

Initial reports placed the quake at a magnitude 6.4, but this was later downgraded to 6.2 by the US Geological Survey.

A number of "strong" aftershocks have also been reported.

One person was killed after being crushed by a collapsing building, and the other by a fire that broke out after the quake.

At least 400 people are being treated at local hospitals, public broadcaster NHK said. Others are feared trapped under fallen structures.

"We will do our utmost and carry on with life-saving and rescue operations throughout the night," Prime Minister Shinzo Abe told reporters.

The earthquake hit close to the town of Mashiki, in the Kumamoto district (Google)

Around 20 houses have collapsed, according to Japanese broadcaster NHK.

A fire also broke out in Mashiki, which has a population of around 34,000 people, and local television showed footage of firefighters tackling a blaze at a building.

Officials said there is no danger of a tsunami and confirmed the region's nuclear facilities have not been adversely affected by the tremors. The plants remain in operation.

However, some gas and power outages were reported in areas close to the epicenter. About 16,500 households in and around Mashiki were without electricity, according to Kyushu Electric Power Co Inc.

Images, not verified by The Independent, have been posted to social media apparently showing some of the damage:

Pictures of the fires, seemingly taken from Japanese television, have also been posted to Twitter:

"There was a ka-boom and the whole house violently shook sideways," said Takahiko Morita, a Mashiki resident.

"Furniture and bookshelves fell down, books were all over the floor."

Kasumi Nakamura, an official in the village of Nishihara which is close to the epicenter, said there was a rattling which started modestly and grew violent, lasting about 30 seconds.

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"Papers, files, flower vases and everything fell on the floor," he said.

Hotel guests wait in a car park after being evacuated following the earthquake (Kyodo News/AP)

Other eyewitnesses reported seeing walls around houses collapsing in the city of Uki, where the city hall reportedly suffered broken windows and fallen cabinets.

Footage on NHK TV showed a signboard hanging from the ceiling at its local bureau violently shaking.

Some train services have been suspended as officials attempt to gather information.

Honda Motor Co suspended output at its motorcycle factory near Kumamoto following the quake, a company spokesman said.

Mitsubishi Electric Corp and tire maker Bridgestone Corp also suspended operations at their factories in the area, Kyodo news agency said.

Prime Minister, Shinzo Abe, said soon after the earthquake: "We intend to do the utmost to grasp the situation. I'm now planning to hear what we have gathered on the situation."

The full extent of the damage is not currently known.

The US Geological Survey said the earthquake was 10 kilometers (6.2 miles) deep.