A wide-spread tsunami warning remains in effect along the Sea of Japan after a magnitude 7.6 earthquake struck Ishikawa Prefecture shortly after 4 p.m. on Sunday.

The major tremor registered the highest intensity of seven on Japan's seismic scale. The meteorological agency says earthquakes of similar intensity will remain a possibility for about a week, and especially in the next two to three days.

The agency says tsunami warnings are in effect for the prefectures of Ishikawa, Niigata, Toyama, Yamagata, Fukui and Hyogo -- all on the Sea of Japan. Tsunami advisories remain for the prefectures of Hokkaido, Aomori, Akita, Kyoto, Tottori, Shimane, Yamaguchi, Fukuoka, Saga and Nagasaki prefectures.

Residents are urged to exercise caution. The National Police Agency says that two people in the city of Nanao, Ishikawa Prefecture, suffered cardiac arrest following the quake.

The city of Wajima reported tsunami over 120 centimeters at 4:21 p.m.

The city of Kanazawa recorded tsunami of 90 centimeters.

Tsunami are expected to repeatedly hit the coast and may become higher. Officials are asking people in areas under tsunami warnings to evacuate immediately, move to higher ground and get as far away as possible from the coast.

Officials in Wajima City say a fire broke out in the center of the city.

Reports of injuries and damage continue to come in. Fire departments and hospitals have told NHK that, as of 11 p.m. on Monday, multiple people were injured in the prefectures of Ishikawa, Niigata, Fukui, Toyama and Gifu. Reports say they were hit by falling objects or suffered broken bones.

Authorities are trying to determine the extent of the damage and mount rescue operations.

The Meteorological Agency says that following the 7.6 earthquake, more 50 jolts have been observed in the region.

An official at a hospital in Suzu, Ishikawa Prefecture says people injured in the earthquake have been brought there.
Some doctors have been unable to reach the hospital due to damage to road. The official also says the hospital is operating with a backup generator.

Medical staff at another hospital in the city of Wajima have been treating patients in a parking area.

Reports of damage continue to come in. In the neighboring prefecture of Toyama, police in the city of Himi say that they have received reports of cracks in roads at several locations.

A city official in Oyabe received several reports of broken water pipes.

Officials in Ishikawa's Nomi City say that about 100 people were taking refuge in the city hall's main building at one point.

Hokuriku Electric Power Company says it has shut down two generators at its Nanao Ota thermal power plant in Nanao City in Ishikawa Prefecture.

Officials say about 34,000 households in Ishikawa, Niigata and Toyama prefectures were without power as of 5:30 p.m.

Meanwhile, no damage has been reported to city gas, LP gas, oil refineries or gas stations for the moment. Authorities are working to determine the extent of the damage.

East Japan Railway Company says operations of the Akita Shinkansen line were suspended at around 5 p.m. The Hokuriku Shinkansen and Joetsu Shinkansen lines have also partially halted service and will suspend some of their lines for the rest of the day. It's not known whether service will resume on Tuesday on the two lines.

The Nuclear Regulation Authority says a blast and the smell of something burning were observed at the Shika nuclear power plant in Ishikawa Prefecture.

The operator says functions using the transformer are currently unavailable. But the plant operator says that the two nuclear reactors at the plant can function properly using alternative systems.

Japan's major telecom carriers say they are suffering service disruptions in the prefectures hit by the earthquakes.

Fixed-line carrier NTT West also says its internet and IP phone services may not be available in some areas of Ishikawa Prefecture. There are concerns that emergency phone services are also down. The company says its telecom facilities have been damaged by the earthquake.

Tsunami are also a risk in neighboring countries.

Weather authorities in South Korea say they have observed tsunami. The authorities say further waves could come and last longer. The country's public broadcaster is urging people in coastal areas to evacuate to higher ground.

Meanwhile, authorities in Russia and North Korea have been urging residents to stay on the alert.