"Five persons led by one Chando Pahalwan attacked the police party when it had gone to prevent an illegal construction in Baldeo town late last evening," said Anil Kumar Rai, Superintendent of Police (rural).
They not only assaulted Sub Inspector Jai Pal Singh Tomar, but also attacked other constables who tried to rescue him, Rai said.
The culprits had fled when a large contingent of police reached the spot.
Hunt for others involved in the attack is on, the SP said.