A teenager was today stabbed to death while another injured in a clash between two groups of students near the bus stand in Karnal city, police said. "The boy, a student of Class XII, was stabbed to death and another was injured in the incident," Deputy Superintendent of Police, Karnal City, Vivek Choudhary said. The accused were at large and police have launched action to nab them, the DSP said. The exact cause behind the clash is yet to be ascertained, he said, adding a case has been registered in the matter.