NEW DELHI (AFP) ― At least 61 people died when a four-storey building in a crowded area of New Delhi collapsed, officials said Tuesday, as rescuers hunted for more victims trapped in the rubble.

Officials said the building in eastern Delhi may have been weakened by flooding brought on by some of the strongest monsoon rains in decades, which burst the banks of the nearby river Yamuna that runs through the city.

Rescue workers and residents worked through the night trying to remove debris after the building caved in late Monday in the congested working-class Lalita Park area of Laxmi Nagar, where narrow lanes made it difficult for rescue services to bring in heavy lifting equipment.

“There are many victims still trapped below the concrete rubble and iron rods. Our challenge is to evacuate them alive,” city police spokesman Rajan Bhagat said.

“We can confirm that 60 people are dead and 80 are being treated in several hospitals.”

Witnesses said they heard shouts for help from under the debris, while residents complained that power cuts and the absence of cranes hampered the rescue efforts initially.

“The building fell like a pack of cards. I saw people high up hanging onto remaining bits of the walls. Some were trying to jump out but they couldn’t, others were trapped,” Gurwinder Singh, a local taxi driver, told AFP.

Girija Devi, a mother of four who worked at a tailoring unit in the building, said: “I was pulled out last night by some of the neighbors but my sister is still stuck below the debris.”

Delhi Chief Minister Sheila Dikshit suggested the building might have been an unauthorised construction, and officials said an inquiry has been launched into the disaster.

“I think it is the carelessness of the builder who did not build a strong enough building to withstand a flood that came about a month ago,” she told the NDTV news channel.

M.P. Singh in the Delhi police control room told AFP that police had identified the owner of the building and would be questioning him shortly.

The building is believed to have been mostly residential, but with some small businesses including a cloth exporting company and a food snacks group.

Many of the injured and dead were pulled out by bystanders from the crumpled slabs of concrete and pulverized bricks and mortar piled up at the site.

Enforcement of building regulations is lax in the Indian capital and minor accidents are common. The construction industry is also riddled with corruption, leading to the use of substandard materials.

The much-delayed and over-budget Delhi Commonwealth Games in October shone an unflattering light on many industry practices.

An investigation by India’s leading anti-corruption body concluded that sub-standard concrete and anti-corrosion coatings for steel had been used in a host of public works, while safety certificates also appeared to have been faked.

“The enquiry that we will set up tomorrow will bring out the truth and will hopefully identify those that are guilty either individually or collectively,” Dikshit said Monday.