Protests by AAP workers outside the BJP offices in the national and Uttar Pradesh capitals against party chief Arvind Kejriwal's detention in Gujarat snowballed into a pitched battle between members of both parties.
In New Delhi, Bharatiya Janata Party activists allegedly pelted stones at Aam Aadmi Party members and the protestors retaliated as latter's "peaceful" protest at BJP's headquarters in central Delhi turned ugly.
While both sides hurled chairs and sticks at each other, police intervened, using water cannons to disperse the crowd.
"Some 10 people were injured in the brawl but none was seriously injured. We have detained 35 people," a Delhi Police official told IANS. An FIR could be registered, if needed, he added.
Angry AAP workers vandalised the BJP hoardings. AAP leaders Shazia Ilmi, Ashutosh and Rajmohan Gandhi were at the protest side.
Ilmi told media persons that it was a peaceful protest but the BJP workers indulged in pelting stones at them.
BJP leaders blamed the AAP for the fracas.
"Do they believe in Maoism," asked BJP spokesperson Ravi Shankar Prasad while another spokesman Nirmala Sitharaman said: "No one should indulge in this kind of destructive politics. What's happening is completely unwarranted, highly condemnable."
In Lucknow, workers and supporters of the two parties fought as the AAP's protests outside the local BJP office turned violent, police said.
Raising slogans like "Modi, Arvind se darta hai, police ko aage karta hai (Modi is afraid of Arvind Kejriwal, puts police in front) and "Modi kuch to sharm karo (Modi, have some shame)", the AAP workers gathered outside the Bharatiya Janata Party office opposite the state legislature on Vidhan Sabha Marg.
Soon BJP workers came out and asked the protestors not to block the entry as visitors were finding it difficult to go in and out but the AAP workers refused to budge.
Soon the two sides came to blows. BJP workers chased away the handful of AAP supporters and some were even attacked with canes and sticks.
Police from the nearby Hazratganj police station reached the spot and dispersed the unruly mob.
The incidents took place barely hours after Kejriwal, who began a four-day tour of Gujarat to check Chief Minister and BJP prime ministerial candidate Narendra Modi's claims that the state was a model of development, was detained by police in a village in north Gujarat.
The former Delhi chief minister was released after 30 minutes.