Nine teachers were injured, two of them seriously, when a group of village people gheraoed and attacked them at the higher primary school in Ashapur village near Raichur on Thursday.
The teachers were attacked over a rumour that they had taught unethical lessons to students.
Tension prevailed on the school premises as the irate mob locked the teachers in a room and staged a dharna demanding their transfer.
The situation was brought under control only when a police team headed by Deputy Superintendent of Police Sridhar reached the spot and released the teachers.
The police have arrested Eranna, Veeresh, Kalmala Babu and Sandeep, son of headmaster of the school Bhanutai, in the case.
Upon inquiry, the police found the involvement of Sandeep and Amaregouda, president of the school development management committee, in spreading the rumour.
The two had forced a group of students to give a false statement about the teachers to a local TV channel on Wednesday, sources said.