A magnitude 6.8 earthquake rocked a wide area of Japan centering on the northeast early Wednesday, the Japanese weather agency said. No tsunami warning was issued.

There have been no reports of injuries from the 6:13 a.m. quake or of abnormalities at nuclear power facilities, but bullet train services were temporarily disrupted on the Tohoku and Joetsu shinkansen lines due to power outages, the Japanese news agency Kyodo reported, quoting local officials and operator companies.

The quake registered upper 5 on the Japanese seismic intensity scale of 7 in Hanamaki in the southern part of Iwate Prefecture, and lower 5 in other parts of Iwate and Miyagi prefectures, the Japan Meteorological Agency said.