The deceased has been identified as Ramvilas Jarika, a resident of West Singhbhum district.
He was apparently disturbed for the last few days. He shot himself with an Insas rifle, district Superintendent of Police Indrajeet Mahatha said.
Mahatha said that the senior officials of the district were busy in a meeting when Jarika committed suicide near the treasury office.
The SP said that just before the incident, Jarika had asked his colleagues, who tried to persuade him not to take the extreme step, to stay at a distance, else he would shoot them.