At least 15 persons were killed in a blast at an explosives manufacturing factory in Maharashtra’s Nagpur district on Sunday morning, police said.The blast took place at the SBL Energy Limited factory, a mining and industrial explosives manufacturer, at Raulgaon in Katol tehsil, a senior police official said.Representatives of SBL Energy Limited told PTI that the incident occurred at the company’s detonator packing unit between 7 am and 7.15 am.The injured were shifted to a hospital in Nagpur immediately after the blast, the police said.A company official said rescue operations were underway and they will release a statement soon.