DEADLY COLLAPSE: At least 15 dead, 150 trapped in India disaster

At least 15 people were killed and another 150 believed trapped when a portion of an overpass under construction collapsed in a congested area in the eastern Indian city of Kolkata on Thursday, police and officials said.

Army troops joined efforts to rescue those trapped inside cars, trucks and other vehicles that lay under massive concrete blocks and metal debris. Witnesses said that emergency personnel were attempting to use their bare hands to rescue those caught under the wreckage.

The collapse occurred in Bara Bazaar, a busy residential and shopping area in the city of approximately 4.5 million people.

"The area was very, very crowded. Motorized rickshaws, taxis ... there was a lot of traffic," one witness told the New Delhi Television news channel, or NDTV.

Another added: "We heard a loud rumble and then saw a lot of dust in the sky."

Huge cranes and other rescue equipment reached the site after the collapse and began clearing the rubble. Workers also used gas cutters to pry open the slabs.

More than 70 injured were admitted to two hospitals in Kolkata, the capital of West Bengal state, hospital officials said. Mamta Banerjee, the top elected official of West Bengal state, said 15 people had been confirmed dead.

Television footage from the site showed people passing water bottles through to those who are crying out for help from beneath the debris. Television images showed the bloody legs of some of the trapped people jutting out of the collapsed girders and concrete slabs.

Some witnesses have been critical of the initial response, with one saying there appears to be very little coordination on the ground.

"The condition is pathetic. At this moment no one has any clue how many people are trapped," a police officer at the scene told Reuters.

O.P. Singh, the head of India's National Disaster Response Force, said the operation was a "very, very challenging task."

Senior police officer Akhilesh Chaturvedi told Sky News that 15 critically injured people had been rescued.

"Most were bleeding profusely. The problem is that nobody is able to drive an ambulance to the spot," he said.

Banerjee visited the collapse site and said a private builder had missed several deadlines for completing the overpass.

The contract for the overpass was signed in 2008 and it was expected to be completed in two years. She accused the previous communist government in West Bengal of not adhering to building regulations.

But a newspaper reported last year that Banerjee wanted the overpass finished ahead of schedule in February, despite concerns from project engineers over whether or not it would be possible, according to Sky News.

"We completed nearly 70 percent of the construction work without any mishap," said K.P. Rao, a top official of IVRCL Infrastructure company, which was building the overpass. "We have to go into the details to find out whether the collapse was due to any technical or quality issue."

"It was a total act of God,'" said his colleague, Dilip, who uses one name.

Building collapses are common in India, where builders use poor enforcement of regulations and use substandard materials.

The Associated Press contributed to this report.