The police have so far confirmed nine deaths in the fire.
The official said, the blaze, which started from a firecracker factory, has been brought under control.
The official said that the rescue operations are underway as more people are suspected to be trapped inside the factory.
The Delhi Fire Services received a call about the fire at the factory around 6.20 pm and 10 fire tenders were rushed to the spot, the official said.
North Delhi Mayor Preety Agarwal has rushed to the spot, a senior NDMC official said.
"The factory falls in the Delhi State Industrial And Infrastructure Development Corporation (DSIIDC) area. North Delhi Mayor Preety Agarwal has rushed to the spot to take stock of the situation," the official said.