A group of youth started pelting stones at police and CRPF near the Akhara Building in Maisuma area, a police officer said.
He said the cops initially tried to chase away the protesters by resorting to baton charge but in vain.
Several tear smoke shells were fired to chase away the protests but the youth kept regrouping to engage the cops, the officer said.
The reason for the sudden break out of protests was not immediately known.