Two Bharatiya Janata Party (BJP) activists were arrested in connection with the incident on Monday, the police said.
Four activists of the ruling Communist Party of India (Marxist) in Kerala, including the SFI leader, and three BJP workers have been hospitalised after political violence erupted at Parassala, the border area of Thiruvananthapuram district.
Abu Thahir, a district committee member of the SFI, was hacked, leading to head injuries.
The SFI is the students' wing of the CPI(M).
Houses and vehicles belonging to both CPI(M) and BJP leaders have come under attacks since yesterday.
Local sources said two houses of CPI(M) leaders were attacked and in retaliation, two houses of BJP leaders were vandalised.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)