A head constable of the Delhi Police, posted in Rohini district, allegedly committed suicide by shooting himself with his service weapon while he was on duty, the police said today. Another constable received injuries while trying to stop the head constable from taking the extreme step last night, they added. Harbhagwan (46) was posted at the Shahbad Dairy police station for the last two-and-a-half years. He shot himself in the jaw and the bullet went through his head and hit Rajesh Gurjar, a constable, in the shoulder, the police said. Harbhagwan, along with two constables — Rajesh and Ashwini — had returned to the police station after patrolling the area. They were discussing their problems among themselves in a drunken state, the police said. The head constable was narrating his marital issues when he broached the subject of killing himself, one of his colleagues told the police. He suddenly took out his service weapon and shot himself, the constable added. Police are probing if work pressure was one of the reasons which drove the head constable to take the extreme step.No suicide note was found, the police said.