A fire official said three people were rescued from the debris of the building in Peera Garhi area in western New Delhi. Thirty-five fire engines were at the site, and the rescue operation was continuing for some people feared trapped there.
An eyewitness told New Delhi Television news channel he heard an explosion around 5 a.m. and the fire station reported the structure collapsed soon afterward.
The fire official spoke anonymously because he was not authorized to release the information.
There were no workers inside the building when the fire broke out around 4 a.m., the police said.
The fire officials received injuries during the rescue work, the police said. They have been hospitalized.
The blaze was extinguished, but a heavy smoke engulfed the rear portion of the building which collapsed. It contained inflammable material like acid and plastic used for making batteries, the police said.
Poor safety standards are a frequent cause of fires in India. Last month, a fire believed to be caused by an electrical short circuit engulfed a building in New Delhi, killing at least 43 people.