A National Police Agency official said the quake destroyed five houses in Hakuba village, host to ski jumping and other events during the 1998 Nagano Winter Olympic Games, but that the 21 villagers trapped were successfully rescued.
At least two of them were injured, although the degree of their injuries was not immediately clear, he said.
|Aerial Photo of collapsed houses in Hakuba|
NHK reported 13 people were injured in the quake, including five who were seriously hurt.
Chief Cabinet Secretary Yoshihide Suga told reporters an advanced party of Japan's military had been sent to the area, and others were on standby.
|Firefighters and Rescuers examine collapsed buildings|
High-speed trains were halted but later resumed service, Kyodo news agency reported.
There were no signs of irregularities at Tokyo Electric Power Co's (TEPCO) Kashiwazaki Kariwa nuclear plant, a spokesman for the utility said. The plant, where all seven reactors are currently off-line, is the world's largest power station.
NHK quoted an official in the village of Ogawa near the epicenter as saying there was a long tremor and documents fell off shelves.
|Residents look at damaged buildings|
"On the second floor of our house, the tremor was too strong to stand," said Sakiko Hagiwara, an NHK employee in the area.
"Pictures fell off the wall," she said, adding there were no cracks in the walls.
NHK also said there was a report of a landslide blocking roads near Hakuba.
|A local community center stands damaged following the earthquake|