TOKYO - A strong earthquake struck Japan early Sunday, killing at least one person, violently shaking buildings and triggering two very small tsunamis which hit the coast, officials and media reports said.

The quake hit shortly before 10 a.m. off the north coast of Ishikawa prefecture (state), Japan's Meteorological Agency said. It had a preliminary magnitude of 7.1. A small tsunami of 6 inches hit shore around 10:18 a.m., public broadcaster NHK said. A second of similar size hit minutes later down the coast.

Television footage from the quake zone showed buildings shaking violently for about 30 seconds.

NHK reported one person died and 40 were injured.

Immediately after the quake struck, authorities issued a tsunami warning for the country's northwestern Sea of Japan coast and broadcasters urged people near the sea to seek higher ground. The Meteorological Agency said seismically triggered waves of up to 25 inches were possible.

Calls to police and local officials in the region were not immediately answered.

The United States Geological Service said the epicenter of the earthquake was 225 miles northwest of Tokyo. The USGS gave a preliminary magnitude of 7.3.

Train service in the Ishikawa and nearby Toyama prefectures was suspended and all Nippon Airways flights between Ishikawa and Tokyo were postponed, Kyodo News agency said.

Nuclear power plants operated by Tokyo Electric Power Co. and Kansai Electric Power Co. were operating normally in Niigata and Fukui prefectures, according to the report.

Japan sits atop four tectonic plates and is one of the world's most earthquake-prone countries.