Updated

A powerful earthquake rocked Japan's northernmost main island of Hokkaido early Thursday, triggering landslides that crushed homes, knocking out power and forcing a nuclear power plant to switch to a backup generator.

The magnitude 6.7 earthquake struck southern Hokkaido at 3:08 a.m. at the depth of 24 miles, Japan's Meteorological Agency said. The epicenter was east of the city of Tomakomai but the shaking buckled roads and damaged homes in Hokkaido's prefectural capital of Sapporo, with a population of 1.9 million.

Chief Cabinet Secretary Yoshihide Suga told a news conference that two people had been confirmed dead. He did not give details.

Japan is used to dealing with disasters, but the last few months have brought a string of calamities. The quake came on the heels of a typhoon that wreaked havoc in western Japan, leaving the main airport near Osaka and Kobe closed after a tanker rammed a bridge connecting the facility to the mainland. The summer also brought devastating floods from torrential rains in Hiroshima and deadly hot temperatures across the country.

The Japanese national broadcaster NHK, citing its own tally, reported that 125 people were injured and nearly 40 are feared missing. Hokkaido's local disaster agency put the number of injured at 48.

Several people were reported missing in the nearby town of Atsuma, where a massive landslide engulfed homes in an avalanche of soil, rocks and timber.

Reconstruction Minister Jiro Akama told reporters that five people were believed to be buried in the town's Yoshino district. Some of the 40 people stranded there were airlifted to safer grounds, NHK said.

Aerial views showed dozens of landslides in the surrounding area, with practically every mountainside a raw slash of brown amid deep green forest.

Airports and many roads on the island were closed following the early morning quake. NHK showed workers rushing to clean up shattered glass and reinstall ceiling panels that had tumbled down in the region's biggest airport at Chitose.

Prime Minister Shinzo Abe said that 25,000 troops and other personnel would be dispatched to the area to help with rescue operations.

NHK showed the moment the quake struck the city of Muroran, with its camera violently shaking and all city lights going black moment later. In Sapporo, a mudslide on a road left several cars half buried.

Power was knocked out for Hokkaido's 2.9 million households. Economy, Trade and Industry Minister Hiroshige Seko told reporters that the extensive power outage was caused by an emergency shutdown of the main thermal power plant at Tomato Atsuma that supplies half of Hokkaido's electricity.

The hope had been to get power back up "within a few hours," Seko said. However, damage to three generators at the Tomato Atsuma plant means that the restoration of power could take more than a week.

Seko said utilities were planning to start up several other thermal and hydroelectric plants to provide at least some power. Altogether peak demand on the island averages 3.8 million kilowatts, stopgap supplies from smaller plants and from the nearby Tohoku region could bring supplies up to 2.9 million kilowatts within days, Seko said. However, that would leave a shortfall of roughly 900,000 kilowatts, causing inconveniences to many in Hokkaido.

In the meantime, authorities sent power-generator vehicles to hospitals so enable them to treat emergency patients, he said.

Reacting quickly to the disaster, troops deployed water tanker trucks in Sapporo, where residents were collecting bottles to tide them over until electricity and tap water supplies come back online.

The quake's impact was widespread. To the north, in the scenic town of Biei, residents lined up outside of supermarkets and convenience stores, quickly clearing shelves of water, toilet paper and food.

"Only a few cartons of instant ramen were left," said Mika Takeda, who lives in the town of 10,000. The one local gas station was limiting customers to only 20 liters (5 gallons) of gas, she said.

As Japan's northern frontier and a major farming region with rugged mountain ranges and vast forests, Hokkaido is an area where residents are used to coping with long winters, isolation and other hardships. But the blackouts brought on by the quake underscore the country's heavy reliance on vulnerable power systems: without electricity, water was cut to many homes, train lines were idled and phone systems stopped in some areas.

Suga said authorities were doing their utmost to rescue and assess damage after receiving hundreds of calls about people missing and buildings collapsing.