About 80 meters (260 feet) of the overpass, which was under construction, fell onto the busy Burrabazar area of the city Thursday, burying pedestrians, cars and auto-rickshaws, with 70 people injured, the local government said.

With more than half the debris cleared by Friday morning, 67 people have been pulled out alive, Kolkata police Sgt. P. Chakraborty said. It is not clear how many are missing, he added.

Hundreds of personnel from National Disaster Response Force (NDRF) used drilling machines, concrete-cutters and sniffer dogs to reach people stuck under the rubble, assisted by army soldiers and policemen.

"Our teams have extricated eight bodies since last night and the death toll is around 24. Our priority is to find survivors, though the possibility of finding anyone alive is very remote," NDRF chief O.P. Singh told reporters.

The operation was a "very, very challenging task," he said, adding that a major section of collapsed overpass had already been removed.

"The area was very, very crowded. Motorized rickshaws, taxis ... there was a lot of traffic," one witness told NDTV television.

Construction of the 2 kilometer-long (1.24 mile) overpass started in 2008 but missed several deadlines for completion because the firm carrying out the work, IVRCL, was in financial trouble, media reports said.

"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."

The overpass spanned nearly the width of the street and was designed to ease traffic through the densely crowded Bara Bazaar neighborhood in the capital of the east Indian state of West Bengal.

Building collapses are common in India, where regulations are poorly enforced and construction companies often use substandard materials.

jbh/kms (dpa, AP, AFP)