Firefighters and helicopter medical teams rushed to the area after the tornado struck the city of Tsukuba, 60 kilometers (40 miles) northeast of Tokyo.
A 14-year-old boy was in serious condition, and 10 others were being treated at hospitals, the local fire department said. Details of their injuries were not immediately available.
NHK footage showed rows of houses that had lost roofs, apartment complexes with smashed balconies and shattered windows, and crooked telephone poles that could barely stand. NHK also showed footage of a swirling gray cloud it said was taken by a passer-by.
The number of homes damaged was still unknown, it said. Initially, the fire department had said 30 to 50 homes were destroyed. NHK TV reported that some 200 homes were damaged.
Tokyo Electric Power Co. said 24,000 homes were without electricity as strong winds and lightning added to the tornado damage. Fukushima Dai-ichi nuclear power plant, which went into multiple meltdowns from last year’s tsunami, was not affected by Sunday’s tornado or storm, TEPCO said.
Tornadoes are relatively rare in the Tokyo area.
