The incident took place last night when a seven-member police team led by ASI Nabin Patel went to tribal-dominated Durbahal village to arrest a man wanted in a case of assault of employees of an electricity distribution company some months ago.
When the person was apprehended, he raised an alarm and other villagers attacked the police party with traditional weapons and injured four policemen.
While the rest of the police team managed to escape, the ASI and the driver of the police jeep were caught by the mob and assaulted, IG of police (Western Range) Y K Jethwa said.
The villagers then tied the two to the seats of the jeep and pushed it to a nearby bridge from where it rolled into the swollen Badjore river. The vehicle was soon swept away by the strong river current.
The driver managed to free himself and swam to safety, but the ASI, who is believed to have succumbed to his injuries, could not be traced last night.
His body was traced this morning three kilometres down stream, Sundargarh Superintendent of Police Sanjeeb Arora said.
The police have arrested six persons, including the elder brother of the arrested man, in connection with the incident, he added.