Four Army personnel reportedly went missing during a mock drill in the Yamuna river at Hathnikund barrage in Yamunanagar district on Tuesday after an Army motorboat developed a technical fault.Three soldiers later managed to swim to safety, while a fourth soldier remains missing. A search operation is underway.According to information, Army personnel had arrived at Hathnikund barrage for a training exercise. An Army motorboat had been deployed in the upstream area of the barrage for the drill, however, the motorboat reportedly developed a technical problem and began sinking.Four soldiers aboard the boat reportedly jumped into the water. Wearing life jackets, they were carried by the strong current towards the Western Yamuna Canal. Three soldiers managed to swim out safely, however, the fourth soldier could not be traced and remains missing.Soon after the incident, a police team from Pratap Nagar police station of Yamunanagar district reached the spot and joined the search operation.Rohtas Kumar, SHO, Pratap Nagar police station said that a soldier of the Army was missing in Yamuna river.“On our request, the authorities of the Irrigation and Water Resources department, has reduced the flow of water in Western Yamuna Canal from the Hathnikund barrage. We have also requested the district administration to send a team of NDRF to carry out the search operation,” said SHO Rohtas Kumar.