At least seven people were killed and eight injured after an explosion in a factory here on Thursday night brought down the building, police said on Friday.The factory, a double-storey building in west Delhi's Sudarshan Park area, was used for painting ceiling fans.Additional Deputy Police Commissioner Sameer Sharma told IANS: "The death toll is now seven. Another person succumbed to his injuries in a hospital."He said the identity of six of the dead was known. The owner of the factory, Ankit Gupta, was among the injured.Sharma said a case had been registered against Gupta, a resident of Rohtak in Haryana.According to the Delhi Fore Service (DFS), which carried out rescue operations, the cause of the deaths were burns and building collapse.Another police official said a gas cylinder exploded, causing the tragedy.Eight fire tenders reached the spot and found that due to the impact of the blast the roof and a portion of the building has crashed. A DFS official also said that a blast led to the disaster.A total of 15 people were rescued from the debris.On January 20 last year, 17 people died after a fire broke out in an illegal firecracker factory in Delhi's Bawana industrial area.