Tension erupted in Assam's Baksa district - a part of the Bodoland Territorial Area Districts (BTAD) - after bodies of four youths were found on Sunday, police said.
The four bodies were recovered from a village called Gerua Ashram under Baganpara police station in the district. All the four bore injury marks, police added.
"Our investigation is on to find out the motive behind the killing and those involved in the crime," a police officer said, adding that local villagers spotted the bodies lying in paddy fields and informed the police.
"Family members of the deceased said that the four were called out of their houses by unidentified people last night and killed," police said.
Baksa, which is a part of BTAD along with Kokrajhar, Chirang and Udalguri districts, had witnessed one of the worst-ever spells of ethnic violence between the Bodos and Bengali-speaking Muslim settlers last year that left over 100 people dead and close to five lakh people displaced.