New Delhi: A Delhi Traffic Police head constable was killed after being hit by an unidentified vehicle while on speed enforcement duty on NH-44 in Narela Wednesday, police said.The accident took place when a traffic team from the Narela Circle, comprising ASI Naresh, HC Vinod and HC Amit, was conducting speed challan enforcement on the highway. During the operation, head constable Amit sustained grievous injuries after being struck by a vehicle.He was rushed to Harish Chandra Hospital, where doctors declared him dead during treatment.Police said Amit, a resident of Sonipat in Haryana, is survived by his wife and two children. His family has been informed.A police team has been formed to identify and trace the offending vehicle.