According to the fire department and police, the fire broke out at around 6.30 pm on Sunday.

The fire spread rapidly in the slum, the locals said. At least 15 fire engines were brought in to control the blaze.

Slum dwellers and the authorities said the explosion of LPG cylinders in some huts caused the blaze.

The narrow slum lanes and the lack of ready water supply added more problems for fire department teams.

The large fire engines could not reach the blaze as they had to refill their tanks from a water source few kilometres away.

The police had sealed off a section of the bypass to let the the fire engines move freely and avoid any major traffic jams from Park Circus side. Residents said they ran out of their homes after they heard several loud explosions.

“We later figured out that it may have been gas cylinders. Most of the material used to build this hut is highly combustible, and the fire spread very quickly. We lost all our personal possessions,” said Rani Mondal.

Fire Department personnel said the single-storey nature of the constructions made it easier for them to douse the flames, though the lack of water was slowing things down.