Reports of the intensity of the quake, centered in the Nagano area at 10:08 p.m., differed. The Japan Meteorological Agency reported it was a 6.8 magnitude temblor; the U.S. Geological Survey (USGS) said it was magnitude 6.2.
Near the epicenter, the quake caused at least five homes to collapse in the village of Hakuba, about 30 kilometers (less than 20 miles) west of Nagano, according to a local official who spoke on condition of anonymity, as is customary in Japan.
At least five people were rescued from the homes and taken to a hospital with injuries, the official said. The nature of their injuries wasn’t immediately known.
In Nagano, the fire department also reported that several people had been injured, according to the Kyodo news agency.
The quake triggered several landslides in the area, according to local news media. Live webcams set up in Hakuba showed that power was still on and did not reveal any damage.
The Japanese government’s chief Cabinet secretary, Yoshihide Suga, said military troops were deployed to the quake area. The epicenter is located in a remote mountainous area in Nagano prefecture.
No electric facilities, including nuclear power plants, were damaged, the Tokyo Electric Power Co. said via Twitter Saturday.
The USGS’s online ShakeMap estimated strong shaking would have been felt near the epicenter, with a potential for light damage.
Aftershocks followed the main quake Saturday night, including one measured at magnitude 4.1, the Japan Meteorological Agency said.
By Yoko Wakatsuki, Junko Ogura and Jason Hanna
CNN’s Yoko Wakatsuki and Junko Ogura reported from Tokyo. CNN’s Jason Hanna reported and wrote in Atlanta. CNN’s Pierre Meilhan contributed to this report.