Constable Sukhram Upadhyaya first shot Assistant Police Inspector Y K Awasthi with his service gun. Awasthi was preparing duty roster of constables on the day of Holi.
Upadhyaya then left the station and shot himself about 100 metres away.
Sources said he was miffed after being put on 'warrant service' duty in another district and had an altercation with Awasthi a few days ago. Further probe is on.