Police have found large quantities of detonators and fuses at the blast site in Yuanping, Shanxi Province.

They said explosives might have been stored in the basement of a two-storey building, which housed a five-room garage on the first floor and 17 accommodation rooms on the second floor.

Initial investigations found that Wang Jinsheng, an administrative officer at Xuangang Coal and Electricity Company staff hospital who previously operated private coal mines, moved dozens of boxes into the garage 10 days before the blast.

Wang held the keys to the garage, and he disappeared at the time of the blast. Police have issued a nationwide arrest warrant for him.

However, the cause of the blast is yet to be officially confirmed and is still under investigation.

Sources with Xuangang Coal and Electricity Company told Xinhua said it was estimated that the boxes allegedly held more than a ton of explosives. They also suggested that Wang bought the explosives when he was running private coal mines.

Rescue teams wound up their work on Wednesday afternoon after recovering 31 bodies.

The explosion took place at about 2:25 a.m. on Monday.

Patients at the hospital, many of whom were injured, have been transferred to Yuanping People's Hospital and Yuanping Railway Hospital.

The explosion destroyed the two-storey building and several small houses nearby. The blast damaged buildings within a one-kilometer radius, causing serious damage to a five-storey medical staff building nearby.

Many of the 200 villagers living nearby were also injured, said a rescue team member.