The incident occurred last night when the tanker's driver Raghuraj Singh and his aide Rafiq had stopped to drink tea at a roadside stall, a police spokesperson said.
The tanker caught fire when the sparks emitting from the earthen stove in the stall came in contact with it and a passerby identified as Vijay, and Singh and Rafiq were caught in the sudden blaze, police said.
The fire was doused after 40 minutes by the fire personnel, they said.
The injured have been admitted to a hospital and their condition is stated to be critical, they added.