Constable Mithilesh Singh, a native of Mau district, killed himself with his service rifle while on duty today morning, Senior Superintendent of Police Akash Kulhari said.
He was rushed to a nearby government hospital, where doctors declared him dead, Kulhari said.
The constable was suffering from some illness and was depressed, the SSP said.
Singh also left a suicide note in which he mentioned illness to be one of the cause of taking this extreme step, and wrote that everyone should forgive him for this act, Kulhari said.