The incident occurred yesterday when a person allegedly passed a comment against a woman under Kairana police station here, flaring an old rivalry between the two groups, they said.
The groups led by Dali and Azad, belonging to the same community, clashed over the issue using lathis and other sharp weapons, they said.
Police said the woman belongs to Azad's group.
Dali and Azad were injured, police said, adding, all 16 injured were admitted to a nearby hospital where some of them are reportedly in a serious condition.