SHANGHAI (Reuters) - Police in Beijing have detained 18 people following a fire that killed 19 people and injured another eight on Saturday evening, the state news agency Xinhua reported late on Monday. The fire took place in three-storey apartment block in Beijing s southern Daxing district. A large refrigeration facility had been under construction in the building s basement, and preliminary investigations suggested the fire may have started there, Xinhua said late on Monday. Seven managers at the apartment block had been detained, along with seven electricity workers and four construction workers at the facility. None of the workers were properly qualified, it added, citing police. Beijing s Communist Party chief Cai Qi has already ordered a city-wide safety check, which will last four 40 days. The official China Daily said the inspections would cover warehouses, factories, wholesale markets, large residential areas and public places like supermarkets and tourist spots.     