A 33-year-old Indian-origin police officer in the US state of California has been killed after being shot by an ``armed`` unidentified gunman while he was conducting a traffic stop. Corporal Ronil Singh of the Newman Police Department was shot and killed during a traffic stop when he was ``working overtime on Christmas night to provide the best for his family.`` ``A few moments later he called out `shots fired` over the radio,`` the Stanislaus County Sheriff`s Department said in a statement, which is leading the investigation. ``Multiple agencies responded to assist, and Singh was found at the scene with gunshot wounds.`` He was transported to a local hospital where he was pronounced dead, the department said.It said the suspect had fled the scene in his vehicle before the police arrived. The department is leading the investigation and have released surveillance photographs of the suspect and vehicle, asking for any information on the identity of the suspect. The California Highway Patrol (CHP) described him as Hispanic. ``Suspect is considered armed and dangerous and may be in possession of a firearm,`` the CHP said.