Tokyo Electric Power Co. said that some 860,000 homes were without power as a result of the quake, but electricity was gradually being restored, according to Kato.
Kato said there was no danger of a tsunami from the quake. He said that some trains in northeastern Japan had stopped running, and that other damage was still being checked.
Video from public broadcaster NHK TV showed some pieces of a building wall had broken off and fallen to the ground, and pieces of glass were scattered at a store. Items fell off shelves because of the shaking, NHK said. NHK aerial footage showed a portion of a highway blocked by a landslide in Soma, a city in Fukushima prefecture.
The extent of damage from the landslide was not immediately clear, Kato said.
He said there were several reports of minor injuries from the quake, such as a man getting hit by a falling object.
The Japan Meteorological Agency said the quake was centered about 55 kilometers (34 miles) beneath the ocean, changing it from the earlier estimate for 60 kilometers (37 miles).
Prime Minister Yoshihide Suga headed into his office immediately after reports of the quake, and a crisis center was set up there. He said there were no reports of major injuries.
“We will continue to respond, putting human lives first,” Suga told reporters early Sunday.