TOKYO >> The operator of Japan’s tsunami-crippled nuclear power plant says about 300 tons of highly radioactive water have leaked from a storage tank there.

Tokyo Electric Power Co. said Tuesday that the contaminated water leaked from a steel storage tank at the wrecked Fukushima Dai-ichi plant. TEPCO hasn’t figured out how or where the water leaked from the tank.

TEPCO said the leaked water seeped into the ground after largely escaping a barrier made of sandbags around the tank. Workers are pumping out the puddle and the remaining water in the tank to transfer the contaminated water to other containers.  

The plant suffered multiple meltdowns following Japan’s massive earthquake and tsunami in March 2011. Leaking contaminated water from elsewhere on the plant also has been leaking into the sea.