At least 15 people were killed and another 19 injured, some seriously, in a major fire followed by a blast in India's biggest Central Ammunition Depot, Pulgaon in adjoining Wardha district in Maharashtra in the early hours of Tuesday, officials said.The figure of casualties, including fatalities is expected to increase even as nightlong fire-fighting efforts continued inside the sprawling CAD.The cause of the blaze is not yet known but fire-fighting operations by the defence fire brigade are underway in full swing at what is Asia's second biggest central ammunition depot.The damage to assets of defence and fatalities, if any are being ascertained, officials requesting anonymity said.Local eyewitnesses said that there were multiple explosions after a blaze due to unknown reasons at the defence depot around 1.30 a.m. on Tuesday.Pulgaon is situated around 40 km from Wardha, the district headquarters, which is 80 kms from Nagpur.