Three days after a group clash in which over 30 fishermen of Jamuna and Patna villages under this block in Puri district were injured over fishing rights in Chilika lake, police arrested seven persons in this connection late Tuesday night. The seven acted as the mastermind of the violence, the police said. They have been identified as Subash Pradhan, Padmacharan Jali, Dhobei Pradhan, Chandan Jali, Rulu Jali, Sugrim Jali and Sibaram Das of Patna village. Acting on a tip-off, police conducted a raid on the village and made the arrests. Meanwhile, Patna village wore a deserted look as all men were on the run in fear of police action. According to sources, Patna villagers had taken on lease the Kahunia- Sagakhia stretch of the lake from 1959 for fishing. A dispute arose after Jamuna villagers started fishing there after forcibly taking possession of the portion of the lake. A case was registered after which the Patna villagers got claim over the lake after a court ruled in their favour. However, Jamuna villagers once again forcibly occupied the lake that led to a clash between the two groups. The fishermen assaulted each other with sharp-edged weapons and lathis. Four persons of Patna village including two women sustained grievous injuries. Similarly, another 13 persons of Jamuna village were rendered critical and all of them were admitted to MKCG Medical College and Hospital.