At least 43 people have died in a devastating fire at a building in a crowded grains market area in central New Delhi, police said.

Firefighters fought the blaze from 100 metres away because it broke out in one of the area’s many alleyways, tangled in electrical wire and too narrow for vehicles to access, authorities at the scene said.

Dr Kishore Singh said rescuers brought victims to his government-run hospital and two others in the city.

Another 16 people were being treated for burns or smoke inhalation and were in stable condition, Dr Singh said.

A view of the factory that caught fire in New Delhi

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Fire Services chief Atul Garg said the blaze was put out by 25 fire trucks and that the rescue operation was completed.

About 60 people, including casualties, were taken out of the building, according to police spokesman Arun Kumar Mittal.

The cause of the fire, which erupted around 5.30 am, was not immediately clear, but police and fire officials said they were investigating whether a manufacturing unit was operating legally in the crowded area.

Distraught people appeared at the site of the blaze and at the three hospitals.

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The Press Trust of India news agency quoted Manoj, who uses one name, as saying that his 18-year-old brother Naveen was working in a handbag manufacturing unit in the building.

“I got a call from his friend informing that he has been injured in the incident. I have no clue which hospital he has been taken to,” he said.

Manoj Tiwari, a Bharatiya Janata Party lawmaker from New Delhi, said most of the casualties occurred on the third floor of the building.

Prime Minister Narendra Modi described the fire as “extremely horrific”.

“My thoughts are with those who lost their loved ones. Wishing the injured a quick recovery,” Modi tweeted.

Authorities are providing all possible assistance at the site of the tragedy, he said.

Fires are common in India, where building laws and safety norms are often flouted by builders and residents.

In 1997, a fire in a movie theatre in New Delhi killed 59 people.

In February this year, 17 people were killed by a fire in a six-storey hotel in the Indian capital that started in an illegal rooftop kitchen.

-AAP