A team of Central Bureau of Investigation reached Bogtui village in West Bengal's Birbhum district on Saturday and started its investigation into the violence that claimed eight lives earlier this week.
Unidentified people had on March 21 set 10 houses on fire in the village, killing at least eight people, including women and children.
The CBI team, consisting of around 20 members, went inside the house where charred bodies of seven people were found.
"We are starting the investigation today. We have to conduct the probe on a war-footing as we have a deadline to meet," the CBI official said.
Sleuths of the Central Forensic Science Laboratory, a unit of the CBI, also visited the gutted houses and started collecting samples.
The Calcutta high court on Friday handed over the investigation into the Birbhum killings to the CBI and set a deadline of April 7 to submit its progress report.