Superintendent of Police R B Singh said an oil tanker in a bid to save a motorcyclist overturned in Sonaideeh locality last evening, leading to a huge oil spill on the road.
Later around midnight, a petromax used for lighting purpose exploded at a nearby house, sparks of which caused the spilled oil to catch fire, he added.
The victims, who were trying to pilfer the oil, got trapped in the fire. Sugreev (28), Golu Rajbhar (16), Pintu Rajbhar (26), Bijendra (25), Ram Pravesh (22) and a unidentified person died on the spot.
The SP said the injured were admitted to the district hospital, where one Sheru Singh (25) with serious burn injuries was referred to a Varanasi hospital for treatment.
Agitated over the incident, local residents blocked Ballia-Lucknow highway and disrupted traffic movement on the route this morning.