Kumamoto city earthquake April 2016
A collapsed house is seen after an earthquake in Kumamoto, southern Japan, in this photo taken by Kyodo on 15 April 2016REUTERS/Kyodo

At least nine people are now known to have perished after a 6-magnitude earthquake struck the southern Japanese island of Kyushu. More are believed to be trapped after buildings collapsed and around 400 people were injured. Video footage showed buildings in flames.

At least 50,000 homes were left without gas or electricity. However, the two Sendai nuclear reactors nearby are said to be functioning as normal and three Genkai nuclear reactors are closed for inspections.

Most of Japan's nuclear reactors remain offline following the meltdown at the Tokyo Electric Power Co.'s Fukushima No 1 plant in 2011 after a magnitude 9.0 earthquake triggered a huge tsunami that knocked out the plant's reactor cooling equipment.

The earthquake occurred at 9:26pm local time (12:26 GMT) on 14 April, seven miles (11 km) east of the city of Kumamoto at a depth of six miles (10 km). According to the U.S. Geological Survey (USGS) the quake was initially estimated at 6.4 magnitude but later revised down.

Aftershocks of 5.7 magnitudes occurred 40 minutes later. However no tsunami was triggered by what is thought to be the strongest earthquake to hit the country since the 2011 disaster.

Of the two confirmed fatalities, both in Mashiki, Kumamoto Prefecture, one was struck by a collapsing wall and the other in a fire which resulted from the quake. Prime Minister Shinzo Abe said authorities would do all they could. "We will do our utmost and carry on with life-saving and rescue operations throughout the night," he told reporters.

Chief Cabinet Secretary Yoshidide Suga said at least 19 houses collapsed, and hundreds of calls came in reporting building damage and people buried under debris or trapped inside. "Because of the night darkness, the extent of damage is still unclear," he said.

Dozens of people evacuated their homes and gathered outside Mashiki town hall, sitting on tarps well after midnight. Some were wrapped up in blankets. Television footage show fires had broken out in some places.

In Mashiki, more than 20 homes have collapsed and several people were trapped. At least seven fires have been reported in the town. Around 1,800 people in Mashiki have left their homes and are spending the night at evacuation centres.

Takahiko Morita, a Mashiki resident, told Japanese TV station NHK the quake struck without warning. "There was a ka-boom and the whole house shook violently sideways. Furniture and bookshelves fell down, and books were all over the floor."

Japan's buildings are built with earthquakes in mind because they are relatively common due to the country's proximity to the so-called Pacific "Ring of Fire." In countries where building regulations are less stringent earthquakes of a similar size would be devastating. The 2011 earthquake was 9 magnitude — one of the largest ever recorded — triggering a monster tsunami and damaging the Fukushima nuclear reactor. Around 20,000 people died in the disaster.