It is feared that up to 30 people are buried under the ground and debris from multiple large-scale landslides that hit sparsely populated fields on the northern island of Hokkaido after a 6.6 magnitude earthquake.
Aerial footage showed smashed farm buildings at the foot of a hill as rescue helicopters buzzed overhead in a region already hit by the strong typhoon that struck parts of Japan earlier in the week.
The earthquake left almost three million people without electricity after damage to a major thermal plant supplying the region, and Industry Minister Hiroshige Seko said it could take "at least a week" for the supply to be restored .
Long lines were formed outside gas stations and supermarkets when residents dug and authorities warned that there might be other tremors on the way.
Kazuo Kibayashi, an official from the hard-hit city of Abira, told AFP: "There was a sudden and extreme jolt, I felt it went sideways, not up and down, for about two or three minutes."
"It stopped before the tremors started, I felt it was coming in two waves, I'm 51 years old and I've never experienced anything like that, I thought my house was going to collapse, everything inside my house was messed up. even to start cleaning, "he added.
Public broadcaster NHK reported that 11 people lost their lives, many of them in the village of Atsuma, where the landslide engulfed their homes. Thirty-two people were still missing, according to the station, with around 300 minor injuries.
The mayor of Atsuma, Shoichiro Miyasaka, promised that the rescuers would work "all night" in an effort to find survivors.
Moments after the initial earthquake, which struck 62 kilometers (39 miles) southeast of the regional capital of Sapporo, a replica of 5.3 shook the area, with dozens more tremors throughout the day.
"We will do our best to save lives," Prime Minister Shinzo Abe said after an emergency cabinet meeting.
Government spokesman Yoshihide Suga added: "I urge people in areas shaken by heavy tremors to remain calm, pay attention to evacuation information … and help each other."
"It's going to rain (in Hokkaido), be very careful with landslides," the spokesman warned.
Some 20,000 rescuers, including police and members of the Self-Defense Forces, responded to the disaster, Suga said. Another 20,000 soldiers are expected to join the effort.
Japan is still recovering from its worst typhoon in 25 years, which hit the western part of the country on Tuesday, claiming at least 11 lives and causing major damage to a major airport.
& # 39; Often great tremors occur & # 39;
The earthquake also caused a major transportation disruption with all flights canceled from the main Chitose airport in Sapporo, where tremors tore down part of the roof and ruptured a water pipe. Local buses and trains, as well as bullet train services were stopped.
The Tomari nuclear power plant in Hokkaido, which was not operational before the earthquake, was forced to resort to emergency backup power to keep its cooling system running, the NHK said.
A friendly football match between Japan and Chile planned for Sapporo was canceled, and the Japanese FA cited the earthquake's severe impact on energy and transport.
The authorities warned of the danger of new tremors.
"Large earthquakes often occur, especially within two or three days (of a large one)," said Toshiyuki Matsumori, who is in charge of monitoring earthquakes and tsunamis at the meteorological agency.
The risk of landslides and landslides in housing has increased, he said, and urged residents to "pay full attention to seismic activity and rain and not enter dangerous areas."
And the national weather agency warned that there could be more bad weather on the road to Hokkaido, asking people to monitor landslides, high tides and heavy rains.
Japan sits on the "Ring of Fire" of the Pacific, where many of the earthquakes and volcanic eruptions of the world are recorded.
In June, a deadly tremor shook the Osaka region, killing five people and wounding more than 350.
On March 11, 2011, a devastating earthquake of 9.0 magnitude shook the Pacific Ocean and the resulting tsunami caused widespread damage and claimed thousands of lives.