Magnitude 6.8 earthquake shakes Nagano, Japan Tokyo - A strong earthquake struck central Japan on Saturday night, causing at least one building to collapse and injuring several people, according to Japanese media reports. No tsunami warning was issued. The magnitude-6.8 earthquake hit parts of Nagano city and surrounding areas the hardest, the Japan Meteorological Agency said. The U.S. Geological Survey measured the quake's magnitude at 6.2. The earthquake struck at 10:08 p.m. Japan time (1308 GMT) at a depth of 10 kilometers (6 miles), but since it occurred inland, there was no possibility of a tsunami. An aftershock with a magnitude of 4.3 followed about 30 minutes later. Japan's Kyodo news agency, citing fire officials, said several people reported injuries, and at least one building collapsed. It wasn't clear whether the injured were at the building. National broadcaster NHK reported that a landslide blocked a road after the quake struck. NHK also said 200 homes were without power, and that Shinkansen bullet train service in the area was temporarily suspended.