A nuclear power station in Hokkaido is relying on emergency backup power after a powerful earthquake knocked out electricity on the northern island Thursday, offering a stark reminder of the 2011 Fukushima disaster.

The three-reactor Tomari nuclear plant, operated by Hokkaido Electric Power Co. and in shutdown since the aftermath of the Fukushima disaster, lost power after a magnitude 6.7 quake hit the island in the early hours, the government said.

The plant's fuel rods are being cooled with emergency power supplied by diesel generators, Chief Cabinet Secretary Yoshihide Suga told reporters Thursday.