The attackers carried jars full of petrol in two totos (battery-run three-wheelers) to Bogtui and emptied the containers through the gap between the door and the floor of a grocery shop.

Inside were 10 members of Mihilal Sheikh’s family, who had taken shelter there to save their lives, a teenager who was among those holed up told The Telegraph on Tuesday.

The arsonists then set the shop on fire, grievously wounding Nazima Biwi, 40. She died at Rampurhat Medical College and Hospital on Monday, becoming the ninth casualty of the Bogtui carnage.

The eyewitness, a 14-year-old boy related to Mihilal, said: “I was returning from my evening prayer when I found several goons and two totos packed with jars. I was scared and I rushed home and took shelter inside the grocery shop along with nine relatives. We bolted the iron door from inside,” said the boy, sitting at a home after being discharged from hospital. The burns, running from his right wrist to way past the elbow, are visible.

A toto lying abandoned in Kumadda. Snehamoy Chakraborty

The attackers fled after setting some houses ablaze but left the totos behind in Kumadda, around 600 metres from Bogtui.

On the night of March 21, at least eight houses were set on fire in Bogtui. Seven charred bodies were recovered from the house of Sona Sheikh. The grocery shop was one of the addresses that became a target on that fateful night.

On Tuesday, this correspondent visited Kumadda village where the boy showed the two abandoned totos. “I think neither the police nor the CBI have checked these totos as of now,” said the boy.

After taking over the probe from the state police, CBI sleuths have been busy trying to find out how the goons set the houses ablaze. The same question has also been in the minds of forensic officials, who found at least two plastic jars in the gutted house of Sona Sheikh.

Later on Tuesday, CBI officers did visit Kumadda village and spoke to the boy to establish the sequence of events on the night of March 21.

The boy told the CBI that the goons failed to break the lock from outside and repeatedly asked the family members to open the door and come out.

“We didn’t open the door and tried our best to ensure that they could not break it open.… Suddenly, we realised that some liquid was gushing in from beneath the door and it smelt like petrol. As most of us were sitting on the floor, our clothes got soaked in petrol. Then someone set the liquid on fire and the room was in flames,” said the boy.

“I saw my relatives in flames but we couldn’t do anything.… After some time, one of my cousins opened the door and some of us fled,” said the boy who was released from the hospital on Sunday.