Maharashtra Navnirman Sena (MNS) activists clashed with Samajwadi Party supporters close to the venue of a rally organised by United National Progressive Alliance (UNPA) in Mumbai on Sunday.
The clash took place before the start of the rally at Shivaji Park where top leaders of UNPA, including Samajwadi Party chief and the group's Chairman Mulayam Singh Yadav, are scheduled to speak.
Some members of the mob were detained and security at the venue in Central Mumbai stepped up, police said.
Activists of both political parties assembled outside the Plaza Cinema in Dadar and indulged in stone pelting. Five cars were also damaged in the incident.
The clash comes hours after actress and Samajwadi Party MP Jaya Bachchan's retaliation to MNS President Raj Thackeray's statement against her husband and superstar Amitabh Bachchan.
Incidents of tearing of posters en-route to Shivaji Park in Central Mumbai allegedly by MNS activists to disrupt the rally have also been reported.