SDO Sudip Sarkar said the girls, daughters of two workers there, were playing at Tinna locality when they fell through a hole in the ground which opens into the kiln.
The opening was covered with a plastic sheet which broke under the weight of the girls.
Angry workers ransacked the kiln, whose owner has fled following the incident.
Uday Rajbangshi, father of one of the victims, said the entire family of the labourers are forced to work there otherwise they do not get paid.