Five people were killed, over 500 people were injured in a magnitude 6.8 earthquake which rocked Niigata prefecture of central western Japan and surrounding areas on Monday morning.

The death toll rose to five after a couple in their 70s died in a hospital in Niigata. Three women in their 70s and 80s died earlier in the day due to the 10:13 AM (01:13 GMT) quake. All were from the most heavily hit city of Kashiwazaki in Niigata.

According to Kyodo News, over 500 injured people were sent to hospitals as to 16:30 PM (07:30 GMT).

The Chinese embassy in Japan said there has been no report of casualties of Chinese people in Japan.

An aftershock measuring 5.6 on the Richter scale jolted the area again on 15:37 PM (06:37 GMT), following over a dozen minor tremors, the Japan Meteorological Agency said. It also warned that more strong aftershocks are expected within the week.

The weather service issued a tsunami warning immediately after the quake and relieved it about an hour later. Over a dozen aftershocks were registered since 10:34 AM (01:34 GMT) in Niigata, with magnitudes around 3 on the Richter scale.

At least 300 houses collapsed due to the strong quake. Over 10 cases of gas leakages were reported, resulting in gas cut in around 35,000 households in Niigata and Nagano prefectures.

A two-car local train in Kashiwazaki derailed due to the strong quake. No casualties were reported as to the case. Monday is a national holiday of Japan.

The epicenter of the major quake was around 17 kilometers below seabed in waters off Niigata prefecture, the agency said. The agency revised the major quake from 6.6 to 6.8 magnitude at noon.

An electric transformer caught fire at the No. 3 reactor of Tokyo Electric Power Co.'s Kashiwazaki-Kariwa nuclear plant. The fire was brought under control around noon, local reports said. Other three reactors at Kashiwazaki-Kariwa nuclear plant automatically shut down. No radioactive leakage has been detected so far.

The quake also caused power failures in over 18,000 households in Niigata. East Japan Railway Co. said it halted bullet train services on the Tohoku, Joetsu and Nagano Shinkansen lines as well as other train services. It said the Tohoku and Nagano Shinkansen lines later resumed operations.

Several parts of highway in Niigata were also closed after the quake. Niigata airport shut down its runways immediately after the quake to check for damage, airport officials said.

The government has set up an emergency management center to handle the quake. Prime Minister Shinzo Abe, who rushed back to Tokyo from southern Japan, is flying to Niigata in a helicopter.

The quake measured upper 6 on the Japanese seismic intensity scale of 7 in Kashiwazaki and Kariwa in Niigata and Iizuna in Nagano, lower 6 in Joetsu and Nagaoka in Niigata, and upper 5 in Iiyama in Nagano. The earthquake also affected nearby prefectures including Ishikawa, Yamagata, Tochigi, Saitama, Fukushima and others.

In October 2004, a major earthquake hit Niigata prefecture, killing 67 people and injuring over 4,800.

(Xinhua News Agency July 17, 2007)