Tokyo (CNN) -- An earthquake with a preliminary magnitude of 6.7 struck off the Pacific Coast of northern Japan early Thursday, Japanese and U.S. seismologists reported.

The Japan Meteorological Agency warned that a tsunami could be generated by the temblor, but canceled the warning less than an hour after the quake.

The coastal cities of Kamaishi and Ofunato ordered about 8,000 households near the coast to evacuate, the Japanese public broadcaster NHK reported, but there was no immediate reports of damage or injuries.

Train service in the area was stopped temporarily, but resumed operation within an hour, NHK reported.

The quake struck shortly before 7 a.m. (6 p.m. Wednesday ET) and was centered 530 kilometers (330 miles) north-northeast of Tokyo.

The epicenter was off the northern prefecture of Iwate, about 175 kilometers (109 miles) north of where the magnitude-9 quake that devastated northern Japan struck in March.

CNN's Kyung Lah and Yoko Wakatsuki contributed to this report.