At least three labourers were on Thursday killed and 23 others injured in an explosion in a firecracker unit in Madhya Pradesh’s Dewas district. The death toll may climb further, official reports reaching here said. “A fire broke out in a firecracker unit located in Tonk Kalan area leading to an explosion in which three people were killed. Around 15 persons were sent to hospitals in Dewas and Indore”, Dewas district collector Rituraj Singh, who inspected the mishap site,