A fire ripped through more than 170 buildings and killed one person in a southern Japanese coastal city on Wednesday, with military and firefighting helicopters scrambling to extinguish the country's largest urban blaze in almost half a century, Reuters reports.

The blaze started on Tuesday evening and has burned 48,900 square meters - roughly the size of seven soccer fields - forcing 175 residents in the hilly Saganoseki district of Oita city, some 770 km (478 miles) southwest of Tokyo, to flee to an emergency shelter, Japan's Fire and Disaster Management Agency said.

The cause of the fire is under investigation, the agency added.

Aerial footage from broadcasters showed houses reduced to rubble and thick plumes of smoke rising from the aforesaid district, which overlooks a fishing harbor renowned for its premium Seki-brand mackerel.

The flames had also spread to nearby forested slopes and an uninhabited island more than one kilometer off the coast, likely due to strong winds, local media reported.

One person has been found dead, local media reported citing police sources, while a woman in her 50s was reported to be hospitalized for mild burns.