The two arrested men were identified as building contractor Gaman Singh and manpower supplier Kailash Pandit, they added.

Due to the palpable danger, the municipal corporation of Delhi (MCD) is likely to backfill the nearly 20-feet deep area, which was dug up for the constructing of a two-storey basement of a residential building, a senior police officer aware of the development said on condition of anonymity.

Both of them were booked on charges of death by negligence and negligent conduct with respect to pulling down or repairing buildings, a case regarding which was registered under the now scrapped Indian Penal Code’s sections 304A and 288 at the Vasant Vihar police station on Saturday, said deputy commissioner of police (southwest) Rohit Meena.

“As the two sections of the law, under which the two were arrested, were bailable, so both of them were granted bail,” added Meena.

Around 5.30am on Friday, six to seven labourers living in makeshift shanties built on the edge of the two-storey basement of a building, which was being constructed over a 500 square yard plot at Vasant Vihar B Block, fell into it after the land under the temporary structures collapsed due to heavy rainfall. Four of them managed to come out on their own, but three labourers were trapped under the debris in the basement.

After a 28-hour rescue operation involving the fire department, Delhi Police, National Disaster Response Force and MCD, the bodies of the three workers, identified as Santosh Yadav,19, his namesake, Santosh Yadav,20, both from Bihar, and Daya Ram,45, from Noida, were recovered from the basement. Even as the construction work was going on after obtaining permission from the agencies concerned, the tragedy highlighted multiple lapses of labour norms, criminal negligence, and treacherous working conditions of the victims and those who survived the mishap, police officers aware of the case said.

Investigators recorded the statement of the other labourers, including the wife of Daya Ram, who were working and living at the construction site. Ram’s wife, Sunita Devi, in her statement told the police that her husband was a mason by profession and she worked with him as a labourer. Apart from the couple, Sunita’s two sisters and their husbands also worked at the site along with the two other dead workers and a few more labourers. All of them were employed at the site through Pandit, said a second police officer, on condition of anonymity.

According to the second officer, Sunita told the police that the four makeshift shanties were built on one edge of the under-construction basement that was dug nearly 20 feet deep for the stay of the workers because the project needed some months to complete.

“Some labourers already refused to stay in the shanties, citing the dangers that the depth of the basement and ongoing construction work posed for them and their children. Sunita and other labourers have alleged that the two contractors assured them that they will be shifted once the construction of the basement and the ground floor of the building was completed,” added the officer.

On Saturday, Delhi labour department officials also said that construction workers should not be allowed to stay under or just next to an under-construction site, considering the magnitude of risk to their life and safety.