Samajwadi Party (SP) president Mulayam Singh Yadav was arrested in Ghaziabad on Thursday when he was on his way from New Delhi to Moradabad, where locals had clashed with police a day before.
Senior SP leader Azam Khan was held at Rampur.
Both Yadav and Khan were released later, but party workers took to streets and blocked the Moradabad-Sambhal highway.
Bharatiya Janata Party national vice-president Mukhtar Abbas Naqvi was also held, and so was Congress MP from Moradabad Mohammad Azaharuddin when they tried to visit Asaalat Nagar village.
The state had clamped prohibitory orders in the area after an angry mob torched a police vehicle on Wednesday.
The clashes began after Taslim, a resident of Asaalat Nagar, accused the police of going on a rampage at his home. According to him, at 8 am, police entered his house and misbehaved with the women of the family. When he resisted, the policemen damaged household goods and showed disrespect to a holy book.
MK Bashal, inspector general, Moradabad, said the allegations were baseless. The rumours, he said, were meant to disrupt communal harmony in the area. According to Bashal, an alert was declared in the area and the situation was brought under control.
Till Thursday afternoon, 38 people were arrested and more raids were on.