A police sub-inspector and a constable died on the spot while another constable was injured in the incident, SSP Anand Dev Tiwari said.
The injured policeman has been admitted to a district hospital, he said.
According to Tiwari, the incident occurred when the police personnel were on their way to nab a criminal in the adjoining district of Gautam Budh Nagar.
Police said that after the incident, the tractor-trolley driver abandoned the vehicle and fled from the spot. However, investigation in this regard is underway.
The bodies have been sent for post-mortem, he added.