The fire broke out around 6:20 pm in the ground floor of the facility - which also has a basement - that has only one exit at the front. Fifteen fire engines were rushed to the spot; rescuers took nearly three hours to put out the fire as search and rescue operation continued late into the night.

As the blaze quickly spread upwards from the basement - trapping most of the workers on the upper floors - two employees, 24-year-old Roop Prakash and 45-year-old Sunita, ran to the terrace and jumped. Both have suffered fractures in their legs.

"One body was recovered from the basement, three from the ground floor and 13 from the first floor," GC Mishra, Director, Delhi Fire Services, said adding that "electric wires in the building were running haywire...There was no fire-fighting arrangement there."

The police said the victims were either charred or were choked to death. Seven of those killed have been identified.

Roop Prakash, one of the survivors, told NDTV that the unit had started operations a fortnight ago. "Chinese firecrackers used to be packed in the building... Only packing of firecrackers used to take place, not manufacturing," he said.

The police arrested Manoj Jain, the owner of the firecracker storage unit, on Saturday night. He claims that his company deals with packaging of low-intensity "cold firecrackers", meant to be sold during Holi and for stage shows. Manoj Jain had rented the factory from January 1, senior police officer Rajneesh Gupta said.

The police are investigating the nature of the explosives used in the said firecrackers and whether he had the license to operate out of the building. Senior police officer Rajneesh Gupta said they were also investigating if firecrackers were being manufactured at the warehouse.

Promising strict action against the guilty, Health Minister Satyendar Jain said, "We have formed a committee to look into the matter. People showed us wrappers of firecrackers, I do not think anyone has a licence to manufacture firecrackers in Delhi," adding it was a serious offence.

The BJP has, however, said that the firecracker factory secured a licence from the Delhi government. "This place, this factory, its licence and everything was with the Delhi government and its industry department. It was being run illegally," Delhi BJP chief Manoj Tiwari tweeted.