A blast that killed 14 people in a block of prefabricated houses in China on Monday was caused by "illegal production and storage of explosives", the state news agency Xinhua reported.



The explosion in the northwestern town of Xinmin in Shaanxi province injured 147 people and damaged dozens of buildings, including a hospital.



"Three suspects were arrested early Tuesday morning. All three confessed their guilt," Xinhua said late on Tuesday, adding that authorities had launched a province-wide investigation into the production and storage of explosives.



The five houses where the blast occurred were rental properties and their owner had been taken into police custody, the news agency said.



It was unclear what type of explosives caused the blast or what their intended use was, but Shaanxi is a coal-mining province and explosives are widely used in the industry.



China has a poor record of industrial accidents.



Previous blasts have been blamed on improperly stored chemicals or industrial explosives. Explosions at fireworks factories are also not uncommon.



A series of powerful blasts last year at a chemicals warehouse in the northern port city of Tianjin killed 165 people.



There have also been cases of people deliberately setting off blasts to settle grievances such as land disputes.