A problem with electrical equipment in the main hall might have caused the fire last week that destroyed Shuri Castle, a symbol of Okinawa located at a UNESCO World Heritage site, according to an announcement made by the fire department of Naha, Okinawa Prefecture on Wednesday.

A surveillance camera captured flashing light in the interior of the burned-down Seiden main hall's northeastern side on the castle's first floor shortly before and after the fire started at around 2:34 a.m. on Thursday, separate sources familiar with the situation said.

When the fire broke out a thermosensitive sensor at the building activated, and the police sources said Tuesday that footage from other security cameras had been obtained showing a flame flaring up on the first floor.