The clash took place yesterday when the inmates were being taken to their barracks, a police spokesperson said.
A team of jail officials, led by DSP Dinesh Yadav pacified the inmates and brought the situation under control, the official said.
The injured, identified as Lalit, Vikas, Shakti, Sanjeev, Kishore and Sourav, were admitted to a hospital here. Of them two were referred to Safdarjung Hospital in Delhi in a serious condition, the spokesperson said.
A case has been registered on the complaint of the jail officials and investigation is on, in-charge of Ballabhgarh Police Station Rajdeep More said.