The deceased were labourers who were working in the factory at the time of the incident, police said.
The exact cause of the fire was yet to be ascertained, police inspector Surinder Chopra.
Around half a dozen firefighting vehicles were pressed into service to put out the fire, he said, adding that it took them three hours to douse the flames
The factory was located in a thickly-populated area of the city, police said.
(With inputs from agencies.)