At least four persons -- all women -- were killed on Sunday in Betul district in Madhya Pradesh after a decommissioned coal mine, where they had gone to collect coal, caved in, officials said."Five women went to collect coal from a decommissioned Western Coalfield Limited (WCL) coal mine in Pathakhera area. When they went deeper, the upper part of the mine caved in," Betul Superintendent of Police D.R. Senwar told IANS."Five women were trapped in the debris. Of them, four have died," the police officer said.The lone injured woman has been admitted to hospital.All women were from underprivileged families. The kin of the deceased would receive compensation, Senwar said. According to locals, people from poor families often collect coal from the decommissioned mine.