The incident took place last night when sub-inspector Manoj Mishra and a constable saw some persons taking away 50-60 cattles.
They detained two of them but when they tried to nab others they opened fire on them, police said.
Mishra was injured in the incident and the cattle smugglers managed to flee from the spot, they said, adding he was rushed to the hospital where he died during treatment.
DIG, RKS Rathore said police teams have been deployed to nab those involved.