The fire at Naya Nagar slum may have started from an electric meter box, the police said.

"The meter box is located in an extremely congested place. A few witnesses told us that they first noticed the fire in the meter box adjoining the rail overbridge early on Friday morning," said BR Gite, inspector, Mahim police station.

The fire spread quickly and destroyed around 50 hutments. "There are many small units near the meter box that stock wood and scrap. Hence, the fire spread quickly and there was a very little time for the residents to react," said Gite.

The officer said they did not suspect any foul play.

Police said there were cylinder blasts, which further increased the magnitude of the fire. "We recovered a charred cylinder from a garage and residents stated they heard a blast," said Gite. 

According to the police, most of the victims were asleep when the started. "It was difficult for the residents to save themselves due to clustered hutments. There was a little space for them to escape and the smoke made things worse," said another police officer.

The firemen also had a difficult time reaching the spot. "The lanes between the hutments were very narrow, which made it difficult for the locals to escape. Even the rescue operations took time because we had to ensure that nobody was stuck in the debris," said a fireman.