The incident happened at Kansara village under Majorganj police station in the district and the deceased has been identified as one Pankaj Kumar Singh (30), the police said.
The injured has been identified as Rahul Kumar, son of a deputy block pramukh (an elected local self-government post) of Majorganj.
Sitamarhi Sadar Deputy Superintendent of Police M N Upadhyaya said, "The incident happened in the evening and is a fallout of previous personal enmity. We are trying to nab the assailants. It is not a clash between two communities."
Sitamarhi Superintendent of Police Hari Prasath S also reached the spot to take stock of the situation.