Eighteen others, 14 of them firefighters, were also injured in the fire that broke out at a battery factory in Peeragarhi district just before dawn on Thursday, Delhi Police said in a statement.

More than 150 firefighters had been called to battle the blaze, which saw flames of more than 10 metres (33 feet) shoot up into the sky, according to reports.

IMAGESA New Delhi factory collapses on firefighters tackling the third major blaze in the Indian capital in less than a month, injuring twelve people. IMAGESA New Delhi factory collapses on firefighters tackling the third major blaze in the Indian capital in less than a month, injuring twelve people. Photo: AFPTV / Atish PATEL

An explosion later rocked the back of the building which collapsed into a heap of debris, giving off black toxic smoke and trapping many inside.

A Delhi fire truck is parked next to the site of a fire and building collapse A Delhi fire truck is parked next to the site of a fire and building collapse Photo: AFP / Aishwarya KUMAR

Two caretakers and a security guard were among those who were rescued.

Emergency services in New Delhi have been put on special alert following a series of high profile disasters in recent weeks.

A blaze that tore through a bag factory on December 9 killed 43 people, while nine others died in a later incident.

Delhi Police is investigating what triggered the blaze.