The fire, apparently caused by a short circuit, broke out early Friday morning in a neighbouring Delhi district at a garment factory in Shahid Nagar area near the Jaipal Chowk, the police said.
By the time fire tenders could douse the blaze, a dozen people were dead, a police official told IANS.
A large number of factory workers, mostly from Bareilly, were present inside the facility when the fire broke out. Only three persons managed to jump to safety.
Senior district officials rushed to the spot as relief and rescue work continued, a state home department official informed.
The injured were admitted to nearby medical facilities.
The victims were identified as Aazad, Fazar, Negwan, Hasmat, Mehboob, Naazim, Sameer, Alauddin, Aamir, Salman, Momin, Naseem and Shakir.