A powerful earthquake that hit Japan’s northernmost main island of Hokkaido early Thursday caused a fire at a Mitsubishi Steel Mfg. Co. factory and prompted a Toyota Motor Corp. unit as well as hundreds of retail stores to suspend operations.

Companies based in Hokkaido scrambled to gather information and assess damage to their facilities after the temblor with a preliminary magnitude of 6.7 struck southern Hokkaido at 3:08 a.m., triggering a blackout across the northern prefecture.

A fire that broke out at Mitsubishi Steel Mfg.’s plant located within an ironworks of Nippon Steel & Sumitomo Metal Corp. in the city of Muroran was later put out, but operations in the Nippon Steel facility have been suspended.

The power outage forced many firms to stop operations and stores to close.

Toyota halted daytime operations at its subsidiary’s transmission manufacturing plant in Tomakomai. The company said it has not decided whether to reopen the factory Thursday evening.

Among retailers, convenience store operator Lawson Inc. closed about half of its more than 600 stores in Hokkaido. Daimaru Matsuzakaya Department Stores Co. and some other department store operators temporarily closed their outlets in the prefecture.

Aeon Co., meanwhile, kept open about 40 supermarkets it runs in Hokkaido, selling water and food.

Japan Post Co. said it has stopped Yu-Pack parcel delivery to Hokkaido, adding that it expects parcel and mail deliveries in the region will be delayed significantly.

Oil distributor Idemitsu Kosan Co. has suspended gasoline shipments at its refinery in Tomakomai due to the power outage.

Hit by the blackout, Hokkaido Bank managed to open 27 branches at 9 a.m. as usual out of its 140 outlets in the region, while Kirin Brewery Co. cancelled a tour at its plant in Chitose on Thursday.