At least eight people were killed and 11 injured in clashes involving two communities at Marad beach near Kozhikode in Kerala on Friday evening, police said.
Policemen, led by Inspector General (North) Venugopal K Nair, rushed to the area, where the situation was tense.
The injured included some women, the police said.
Six of those killed were identified as Gopalan (40), Santosh (24), Chandran (40), Madhavan (45), Haskar (25) and Krishnan (50), they said.
The Marad beach, located in the Beypore police station limits, had witnessed widespread clashes in the past and five persons were killed there over a year ago.
The Rashtriya Swayamsevak Sangh called for a dawn-to-dusk hartal in Kerala to protest against the violence.
Emergency services will be exempt from the hartal, RSS sources said.