A rescue worker carries an injured girl at the site of a building collapse in New Delhi November 16, 2010. A residential building collapsed in Lalita Park in New Delhi's Laxmi Nagar area on Monday evening. [Photo/Agencies]

NEW DELHI - Rescuers hammered slabs of concrete and dug with their hands Tuesday to pull survivors and bodies from a five-story apartment building that collapsed into a mountain of rubble in a poor New Delhi neighborhood. At least 65 people were killed and scores injured.

The 15-year-old building housing hundreds of people _ mostly migrant workers and their families _ collapsed Monday evening in New Delhi's congested Lalita Park area, where emergency efforts were hampered because vehicles had difficulty navigating its narrow alleyways.

"The scale of the tragedy is unprecedented," New Delhi's top elected official, Sheila Dikshit, said as she toured the site.

Residents said they heard a rumble like thunder as the building collapsed upon itself. Then they sprinted to the site.

"There was nothing left, only people helping each other. There were so many dead bodies, there was no movement at all," said Dil Nawaz Ahmed, a 25-year-old journalist who lives nearby.

He dug into the piles of concrete, bricks and mortar with other volunteers and managed to help free five injured residents, he said. But he mainly pulled out bodies, which he carried to waiting ambulances several buildings away.

M.D. Shahanawaz, a 23-year-old student, teared up as his hopes for a friend who lived in the building dwindled.

"He's dead," he said. "Everybody is coming out critical or dead."

The cause of the collapse was not immediately clear. One official said the building may have been weakened by water damage following monsoon rains; Residents said the landlord was illegally constructing an additional floor on the building.

Officials ordered the evacuation of at least one other nearby building that they feared could collapse too, Dikshit said. It also had a flooded basement.

Police said they had filed charges against Amrit Singh, the owner of the building, and a search was on to locate him. Residents said he fled the area right after the building collapsed.

Local volunteers digging for survivors with their bare hands eventually were joined by police and firefighters, who used jackhammers to cut through the iron rods jutting from the wreckage. Police brought in sniffer dogs to locate people trapped under the debris.

Many rescuers were still working with sledgehammers and their hands Tuesday to remove the rubble stone by stone and pull out bodies as neighbors watched from nearby rooftops.

When workers carried a body away from the site on a stretcher, nearby rescuers stopped what they were doing and clasped their hands together in respect for the dead.

At one point, the rescuers uncovered the body of a small child.

One woman whose granddaughter was killed wailed in grief from a nearby roof.

By Tuesday afternoon, at least 65 bodies were recovered and another 80 people were injured, city police official Mohammed Akhlaq said.

Lalita Park is a congested neighborhood near the banks of the Yamuna River that houses some of the millions of impoverished workers who stream into New Delhi from rural villages hoping to get jobs in the growing Indian capital.

"A large number of people come to Delhi in search of jobs. This was cheap accommodation for a lot of them," said Deep Mathur, a city official.

Poor construction material and inadequate foundations often are blamed for building collapses in India. In New Delhi, where land is at a premium, unscrupulous builders often break building laws to add additional floors to existing structures.

Dikshit blamed the builder for the poor construction and maintenance of the building and said the government would probe whether he had the necessary permits to add floors.

The building _ like its twin next door, which was evacuated by police _ was constructed of crude brick masonry with splintered wooden window frames in a neighborhood of muddy, narrow streets.

It housed migrants from the states of Bihar and West Bengal in 80 rooms, with anywhere from three to six residents in each room, residents said. The rooms rented for 2,000 to 3,000 rupees ($44 to $66) a month.

Yoginder Chandolia, another city official, said water from this season's unusually heavy monsoon rains _ which forced the Yamuna to overflow its banks _ had sent water cascading into the basement of the building.

"During the recent flood, water reached the building's foundation and weakened it considerably, resulting in the collapse," he said.

Residents were angry that police and firefighters took so long to arrive after the building collapsed about 8:15 pm Monday.

"They took more than 45 minutes to reach the site. And then there was confusion about how they were going to bring in the ambulances," resident Mohinder Singh said.

But municipal officials said they had enormous problems navigating the narrow alleyways.

"Our biggest hurdle was to get vehicles through. Even ambulances got stuck," said Mathur.