An ex-serviceman in Gurgaon was shot dead by another ex-armyman near here on Sunday night, and the accused was found dead on the railway track on Monday, police said.Rajesh Kumar, 40, was gunned down by his friend Jagdev Yadav, 41, who too was a retired soldier.The incident took place in the Sampka village here on Pataudi Road Sunday night around 11 p.m.Later, on Monday, the body of Yadav was found on the railway track near Jatola, some 2 km from his village Sampka.Yadav visited Rajesh's house on Sunday for some work. Rajesh's another friend, Vinod Kumar, was also present there."After an heated argument over some issue, Yadav shot twice at Rajesh at point-blank range with his licensed revolver...," Assistant Commissioner of Police Rajesh Kumar told IANS.He said: "Vinod also received two gunshots and has been admitted to a private hospital. We are waiting for Vinod's statement to know what actually happened.""Yadav might have committed suicide by jumping before a moving train. We are investigating further. As of now, we cannot ascertain the cause behind the incident," the officer added.Yadav and Rajesh both worked as security guards with two banks in Gurgaon and Delhi.