The incident happened last night when a quarrel between two children escalated into a brawl between two families Kairana town of the district, according to ASP V K Mishra.
The clash turned violent when both sides resorted to swords, lathis and stone-pelting upon each other, he said.
Later, police rushed to the spot and brought the situation under control, he said.
The injured including -- Jahangir, Munir, Tanvir, Imaran, Tohid, Naeem and Waseem -- were rushed to hospital, he said, adding that two head constables, Ompal Singh and Yashpal, were also hurt in the incident and are under treatment.