At least 43 people died in a devastating fire which broke out at a crowded grain market in central New Delhi on Sunday, police said.

Firefighters could only fight the blaze from 100 meters away, as it broke out in one of the area's many narrow alleyways, crisscrossed with 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, Singh said. Fire Services chief Atul Garg, meanwhile, said the blaze had been put out with the help of 25 fire trucks and that the rescue operation was complete. Around 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 a.m., 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 onlookers gathered at the site of the blaze as well as the three hospitals used to treat victims.

The Press Trust of India news agency quoted Manoj, using only his first name, as saying that his 18-year-old brother Naveen had been working in a handbag manufacturing unit in the building.

"I got a call from his friend informing that he had 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, partly due to the fact that building laws and safety standards in the country are often flouted by builders and residents.

In 1997, a fire in a movie theater in New Delhi killed 59 people. In February this year, 17 people were killed by a fire in a six-story hotel in the Indian capital that started in an illegal rooftop kitchen.