The incident took place outside the Bharatiya Janata Party (BJP) state headquarters, when hundreds of Samajwadi Party workers started protesting against the railway fare hike effected late on Friday by the BJP-led union government.
Carrying placards and raising anti-BJP slogans, Samajwadi Party workers burnt an effigy of Prime Minister Narendra Modi.
When BJP workers came out to protest, the Samajwadi Party workers began pelting stones at them.
The BJP workers retaliated and raised anti-Samajwadi Party slogans and slammed the state government over the poor law and order situation in the state.
A melee broke out and angry Samajwadi Party workers indulged in further violence.
While all this happened, policemen remained mute spectators.
Commuters on the busy Vidhan Sabha road were stopped and traffic was blocked on the road.
Police said the matter was sorted out and heavy police deployment was ordered to check any further violence.
State BJP president Laxmikant Bajpayi staged a sit-in at the office of the Lucknow senior superintendent of police and said he will not call off the sit-in until competent officials came and met them.
He also accused police of inciting the violence and said the district administration remained mute spectators to the vandalism of the ruling party workers.
"I specifically charge the additional district magistrate and senior police officials of patronising the mischief makers," he told IANS, demanding tough action against such elements.
The two parties have been at daggers drawn ever since the Samajwadi Party lost to the BJP in the Lok Sabha elections.
The BJP along with its ally Apna Dal won 73 of the 80 seats in the state while the Samajwadi Party's numbers slipped to five. In the aftermath of the poll results, four BJP leaders have been shot dead and many others attacked, leading to allegations that the Samajwadi Party was indulging in politics of vendetta.