One couple died after a blast in a residential building Wednesday morning in Changsha, capital of central China's Hunan Province, Xinhua quoted police as saying. An initial investigation showed that the blast happened at 7:50 a.m. in a rented flat on the fourth floor of the building in Yuhua District, the district police said. The blast caused no other casualties. The police excluded the possibility of a gas leak triggered explosion. The first floor of the building is a wholesale vegetable market. Business resumed Wednesday afternoon.