A fire has swept through a historic castle on the southern Japanese island of Okinawa , destroying much of a structure that had come to symbolise the ancient Ryukyu kingdom and the island’s recovery from the second world war.

Flames engulfed Shuri castle, a Unesco world heritage site located in the island’s capital Naha, at around 2:40 am and quickly spread to other buildings in the complex, local police said.

There were no initial reports of injuries, but nearby residents were evacuated while firefighters spent several hours attempting to bring the fire under control.

The castle, a popular tourist spot, dates back to the days of the Ryukyu kingdom, which began in 1429 and ended in the late 1800s when it was annexed by the government in Tokyo.

More recently, the castle has come to symbolise Okinawa’s struggle to overcome the devastation of war. More than 200,000 Americans and Japanese, including around a quarter of Okinawa’s civilian population, died during a fierce 82-day battle from April to June 1945. The island is still home to a large number of US military bases.

As the headquarters of the imperial Japanese army, Shuri castle was relentlessly shelled by US forces, who occupied the island until it reverted to Japanese control in 1972, two decades after the rest of Japan regained full independence. The castle was extensively restored and reopened as a national park in 1992.

“The cause of the fire has not been determined yet but a security company alarm went off at around 2.30 in the morning,” Ryo Kochi, a spokesman with the Okinawa prefectural police said.

“It started at the main temple and looks to be spreading fast to all the main structures ... firefighters are still battling the fire,” he added.

Television footage showed the multi-structure castle reduced to a skeleton, shrouded in flames and smoke hours after firefighters were alerted to the fire, public broadcaster NHK said.

While the cause is unknown, the blaze is believed to have started in the castle’s main structure. The main Seiden temple and a Hokuden structure, or north temple, burned down and a third building was nearly destroyed, Kochi added.

He said a tourist event was being held at the castle from the 27 October, and some work linked to the event continued until 1 am but it is not clear whether that was linked to the fire.

Nearly a dozen fire engines were dispatched to the scene, Kyodo news agency said.

Thanks to the faithful nature of the postwar reconstruction, Shuri castle was registered as a world heritage site in 2000 along with the surrounding complex and other Ryukyu sites in the region.

“Five hundred years of Ryukyuan history [12th-17th century] are represented by this group of sites and monuments,” the Unesco website says.

“The ruins of the castles, on imposing elevated sites, are evidence for the social structure over much of that period, while the sacred sites provide mute testimony to the rare survival of an ancient form of religion into the modern age.”

Unesco was particularly impressed by the reconstructed main hall of the Shuri castle, describing it as “a great monument symbolising the pride of the Ryukyu people”.