Head Constable Major Hussain and Constable Sunil, who were patrolling the MB Road near Pul Prahladpur, were injured in the attack near the Institute of Child Development on Wednesday.
During patrol at around 10 PM, the duo saw a traffic jam and came to know that it was due to an altercation between a truck driver and a biker after a minor accident.
The two stopped and began to regulate traffic. It was then the errant truck driver and others started pelting stones at them.
Two of the attackers, identified as Parmeshwar Yadav, 25, and Virender Yadav, 23, were arrested from the spot.
The incident came a day after Joint Commissioner of Police (Traffic) Satyendra Garg and another senior officer had a close shave when a truck tried to mow them down despite being flagged down near the DND flyway.