Curfew was imposed in three areas of the district on Saturday after stone pelting by members of two communities.
Police said a procession on the seventh day of Muharram in Khunipur area on Saturday morning was disrupted due to stone pelting from nearby houses. This was retaliated by the other side.
Over a dozen people were injured in stone pelting from both sides, police said. An angry mob also set fire to a mazaar and a car and there were also reports of firing in the area. But there was no confirmation of this.
District Magistrate Hari Om and SSP Raja Srivastava reached the spot and imposed an indefinite curfew in Rajghat, Tiwaripur and Kotwali areas.
No arrests have been made, police said.
Meanwhile, on getting the news of the incident, local BJP MP Yogi Adityanath and MLA Radhamohan along with other party activities staged a dharna demanding imposition of curfew and arrest of culprits.
Earlier, a youth was shot dead during a marriage ceremony at Tiwaripur area on Friday night. Local people and Hindu organisations linked the incident to communal killing.
However, police denied any link between the murder and Saturday's clashes.
The situation in the area was tense with heavy deployment of security forces.