Authorities are finding it difficult to identify some of the bodies from Wednesday's hotel fire in Shenzhen as many of the victims' families live in distant provinces. At least 12 bodies at the Shenzhen Funeral Parlour still have to be identified before being cremated. The blaze at the Duan Xi Hotel killed 29 people and injured 13. 'A few of them were badly burnt to a degree that makes them hard to identify. 'But the main problem came from the distant families being difficult to track down,' Li Xiaogan , a Shenzhen Government spokesman, said. Initial investigations showed the fire was sparked by a short-circuit in the disc jockey's room on the first floor. The room was attached to 12 individual karaoke rooms, separated only by planks of wood, which caused the fire to spread quickly. Authorities were to carry out further examinations before announcing the official cause. A Hong Kong Home Visit Permit was found in a seventh-floor room, but a spokesman said the man was not on the list of dead or injured. 'He probably just left his travel document in his friend's room,' he said. Hong Kong resident Ching Wing-chun was slightly injured in the fire on Wednesday, his two mainland sons were confirmed dead, while his mainland wife and daughter were still in critical condition.