The accused include the mill director, Arif, and a labour contractor, Samir, police said.
Meanwhile, protests broke out near Nagla village as people demanded justice in the case and blocked the Panipat-Khatima highway for several hours with the body of the victim.
The 38-year-old woman was working as a labourer in the paper mill where she was allegedly raped and murdered two days ago.
Police said the mill was owned by a BSP MLA.