Fourteen persons were working in the factory when the explosion took place yesterday evening in Chainpura village, Kethoon police station SHO Dhanraj Meena said.
The factory was gutted in a blaze sparked by the explosion. Fire fighters took around four hours to control the flames and rescue operation lasted till late night, the SHO said.
The intensity of explosion was so powerful that some buildings near the factory developed cracks in walls and the blast was heard in areas within a two-km radius.
Six labourers -- Manisha (20), Indirabai (40), Leeldhar (28), Ramavatar (26) and Modulal (68) -- sustained severe burn injuries and are undergoing treatment in a Kota hospital.
A case has been registered against the owner of the cracker factory Prem Chand Gupta and his sons and further investigation into the matter is underway, the SHO said, adding the cause for the explosion is yet to be ascertained.