The sketch of one of the eight accused was prepared on information by an injured policeman in the attack, SSP KB Singh said.
The assailants had attacked a patrolling team after their car was intercepted and checked near Biralsi village under Charthawal police station on Monday.
No arrests have been made in the case so far, police said.
A reward of Rs 50,000 was announced yesterday for information about the miscreants.
Two police constables, Lakhpat and Dinesh sustained bullet and weapon injuries respectively in the attack. The culprits also looted two police rifles and 40 cartridges from the policemen.