A tsunami warning has been issued after a strong earthquake struck the Japanese capital Tokyo Tuesday morning.

 VOA correspondent in Tokyo, Steve Herman, says the quake measured a 6.8 on the Richter scale, and caused buildings in downtown Tokyo to sway. 

Train service has been suspended in the region, as well as work at a nuclear power plant.

Initial reports say about 80 people were injured in the northern city of Sendai when the roof of an indoor pool collapsed.