At least 27 people died and dozens more were injured in a massive fire in a building in the Indian capital New Delhi on Friday, emergency services said.

The large fire broke out at a four-storey commercial building in west Delhi in the late afternoon, but its cause was not immediately clear.

"Twenty-seven charred bodies were recovered from the building and almost two dozen injured are undergoing treatment," Satpal Bharadwaj, who was in charge of operations for the Delhi Fire Service at the scene, told AFP.

Bharadwaj said there were about 70 people in the building when the blaze erupted.

"There was no fire exit and most of the people died due to asphyxiation," he said, adding that more would be known after autopsies could be conducted.

The official said "almost two dozen" were injured and undergoing treatment, but earlier, deputy chief fire officer Sunil Choudhary told AFP that the number of injured stood at "more than 25 people".

Choudhary added that some had jumped from the burning building.

Broadcaster NDTV, meanwhile, reported that more than 40 people had sustained burns and were hospitalised.

While Bharadwaj said the cause was still not known, he did say the building was used for "offices and storage for paper packing material."

NDTV quoted police official Sameer Sharma as saying the building housed the office of a security camera and router manufacturing company.

Several officials said they believed the death toll could rise.

More than 30 fire trucks were at the scene, along with ambulances.

Amit Mahajan, whose cousin and nephew were missing after the fire, told AFP they had been at the building to "train workers".

"I have visited all the nearby hospitals but there is no trace of them. We are not sure about their safety or whereabouts," he said.

Firefighters in New Delhi said 27 bodies were found at the scene of the blaze
Firefighters in New Delhi said 27 bodies were found at the scene of the blaze AFP / Jalees ANDRABI

Fires are common in India due to poor building practices, overcrowding and a lack of adherence to safety regulations.

A police officer told AFP on condition of anonymity that one of the office owners has been detained for questioning.

The officer was unable to explain the reasons for his detention but said that more arrests could follow.

The Indian capital of 20 million people is currently suffering through a heatwave, with temperatures of up to 46 Celsius (115 Fahrenheit) recorded in some places.

Last month, the heatwave caused a huge trash dump to catch fire. It burned for days, adding to the megacity's deadly air pollution.

Prime Minister Narendra Modi offered his condolences to loved ones of the fire victims via Twitter.

"Extremely saddened by the loss of lives due to a tragic fire in Delhi. My thoughts are with the bereaved families. I wish the injured a speedy recovery," Modi said.

"Distressed by the tragic fire accident... My condolences to the bereaved families. I wish for speedy recovery of the injured," President Ram Nath Kovind's office tweeted.

Delhi Chief Minister Arvind Kejriwal tweeted: "Shocked and pained to know abt this tragic incident. I am constantly in touch (with) officers. Our brave firemen are trying their best to control the fire and save lives."

More than 40 people died in a fire in a factory making school bags and shoes in Delhi in December 2019.

As is often the case, many of the dead were poor migrant workers earning a pittance and sleeping at the factory.

One of India's worst fires was in 1985 at a school in the northern state of Haryana when 442 people died, 258 of them children.

Fires also compounded India's woes during the height of the coronavirus pandemic last year, with a series of blazes at hospitals.

Sixteen 16 Covid-19 patients and two nurses were killed in a fire at a hospital in Gujarat state in May 2021. Another fire killed 22 in Mumbai the month before.