Police said the traffic personnel intercepted the youths as they were driving without wearing helmet.
During heated exchange of words between the youths and the constables, the youths attacked the cops with a knife, police said.
The injured police men were identified as Odisha Special Armed Police (OSAP) member Mahendra Biswal, and constables Rohan Swain and Gyanaranjan Das.
They were admitted to the Capital hospital here in a critical condition.
Meanwhile, police detained the two youths and kept them at the police station here.