The three were employees of the industrial unit in Ugoke village, Senior Superintendent of Police Harjit Singh said.
Singh said fire-fighters struggled for nearly six hours to bring the blaze under control. Fire tenders from adjoining districts were also pressed into service.
A government spokesperson later said the fire had been extinguished.
The cause of the fire is being investigated, the SSP said.
Gupta and other senior officials visited the site and met the families of the victims.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)