The clash took place last night in North 24-Parganas district, DCDD Ajay Thakur said, adding police is enquiring into the incident.
The injured leaders include Centre of Indian Trade Unions (CITU) leader Subhas Mukherjee and former MLA Manas Mukherjee.
Senior party leader Nepal Deb Bhattacharya alleged that Trinamool workers had beaten up the CPI(M) cadres and leaders.