The fire-fighting operations at a battery warehouse in Delhi's Peeragarhi were about to begin when a part if it collapsed, burying four people including three firemen, one of whom died later.
Amit Kumar Balyan, 28, died trying to save lives during the building collapse, where seven fire tenders were rushed.
More than 300 firemen were involved in the fire-fighting operation and 50 fire tenders were deployed, said Atul Garg, Director of Delhi Fire Service.
There was no one inside the building when the fire broke out, but the main challenge firefighters often face is the lack of complete information during the fire call, he said.
"We are not aware of what is inside the building. The fire was completely controlled and the firemen were coming downstairs. There was a fire in the basement and the firemen were trying to douse it when a sudden blast took place leading to a partial collapse of the building," he added.
Later, the firemen managed to continue their operation. Because the impact of the collapse was such that the entire building collapsed in phases, the official said.
"We had all the resources and cranes but despite available resources, we were unable to utilise them because people were trapped inside and the other portion of the building would have collapsed eventually," Mr Garg said.
The other portions of the building eventually collapsed in phases.
It's difficult to ascertain now whether the building had any fire safety equipment, he said.
Around 6.20 am, a blast took place and a porting of the building collapsed and people were trapped, including three fire personnel, he said.
The civilian who was trapped inside the building had come later to get something, he said.
"I was involved in firefighting and started clearing the debris. I was informed that the fire was under control but later I got to know that our firemen were trapped under the debris after a portion of the building collapsed," Mr Garg added.