After getting to know that a group of miscreants were being held by the locals here last night, home guard Amar Singh immediately rushed to the scene, ASP V K Misra said.
Singh caught one of the miscreants and wanted to hand him over to the police, when the accused fired at him in a fit of panic. The unknown assailant later fled from the spot.
The guard's body has been sent for postmortem, he added.
A case has been registered and efforts are on to nab the culprits, he said.