Two people were killed and two others injured after a water heater exploded in a boiler station in a factory in central Russia\'s Udmurtia Republic on Thursday, the regional emergency department said. \"A blast went off in a firewood boiler house in the Sharkan district of Udmurtia at 09:20 Moscow time (0520 GMT). One worker was killed at the scene and another died at a hospital,\" spokesman for the Volga regional Emergencies Center Oleg Zugeyev was quoted by Interfax news agency as saying. Two more workers were still in hospitals and parts of the boiler\'s building collapsed after the explosion, the spokesman added. [ An investigation into the accident is underway, he said.