A 7.4-magnitude earthquake struck off the coast of Fukushima in northern Japan on Wednesday evening, killing at least 2 people and injuring 91, cutting off power for more than 2 million homes in the Tokyo area and triggering concerns over the crippled Fukushima Daiichi nuclear power plant.

Japanese Prime Minister Fumio Kishida said at a news conference early Thursday that the government was still working to assess the extent of any damage after the tremor.

The region was struck by a 9.0-quake and tsunami 11 years ago which resulted in a nuclear crisis due to reactor meltdown.

According to Tokyo Electric Power Company, operator of the Fukushima Daiichi nuclear plant, workers found no abnormalities at the site, which was in the process of being decommissioned.

In the Tokyo region, a total of more than 2.2 million households, including about 700,000 in Tokyo city, were plunged into darkness, said TEPCO Power Grid and Tohoku Electric Power Network. But power was later restored to most of them.

A bullet train with about 100 passengers on board derailed between Fukushima Station in Fukushima and Shiroishizao Station in Miyagi, but no injuries were reported.

A spokesperson for the Chinese embassy in Japan told China Daily"There is no report of casualties of Chinese citizens at the moment and we are continuing to investigate into the situation."