Four people have been arrested in connection with the beheading of two Dalit men in the district of Chidambaram in southern Tamil Nadu state, local media have reported.
"We have arrested four persons and further investigation is on, we are looking into several aspects," A Radhika, superintendent of police, told the local PTI news agency.
The brothers, Ambulance Kumar, 40, and Rajesh, 30, were hacked to death by a gang while they were asleep at home on Monday night, The Hindu newspaper reported.
The brothers were beheaded before being dumped at the entrance of Rajah Muthiah Medical College Hospital.
NDTV reported that police were considering the murders to be the work of a rival gang. The murders of the two men also came as family of the deceased were also attacked at a post-wedding ceremony in the same evening.
At least six people were injured when the attackers allegedly threw explosives at the family members.
A Dalit group, Viduthalai Chiruthaigal Katchi, held a protest in the district on Wednesday.
The group said it would not hesitate to pursue legal steps to get a probe instituted "if the state government did not order an investigation by the federal agency".
On Wednesday, the severed heads and bodies were taken for a post-mortem, but their family members reportedly refused to perform funeral rites until the attackers were arrested.