The building, known as Hostel Daze, collapsed in the Satya Niketan neighbourhood near Delhi University's South Campus at around 13:30 local time on Sunday.

Authorities have not confirmed how many people remain missing.

Rescue workers used heavy machinery to clear debris as emergency crews searched the site. Residents also gathered near the collapsed building.

One eyewitness said he watched the entire structure come down within about 10 seconds and claimed concerns had been raised about the building for years.

"Who will take the responsibility? The building was blacklisted from the last three years - no one has come from the inner city; no one has come from the any government ," he said.

"The students from the PG had filed a complaint to the manager, but he didn't respond immediately to take action," he added.

Delhi Chief Minister Rekha Gupta said on Monday morning that about 80 per cent of the debris had been cleared, with rescue work continuing in the basement.

She said water had accumulated in the basement while repair work was being carried out on the ageing structure.

Local reports initially suggested between 40 and 50 people may have been inside when the building collapsed. Officials have not confirmed the number of occupants or how many remain unaccounted for. The NDRF also said it did not have a specific figure for those potentially trapped.

The disaster has raised concerns among residents about older buildings in the neighbourhood, where many properties are used as private accommodation for university students.

"If you look at it, all these buildings are 40 to 50 years old. So, if a building is 50 years old, it was built back then for just a first or second floor. But why are fourth and fifth floors being built on them?" one local said.

"And they aren't satisfied with just that. In the pursuit of making money, they keep digging basements as well," he added.

Delhi Police registered a case against the alleged owner of the collapsed building. He was later apprehended in Bhiwadi, Rajasthan.

Authorities have ordered action against illegal five-storey buildings and structural safety checks on properties used as paying guest accommodation and other public facilities.

Five municipal officials have also been suspended following the collapse.