Indian rescue workers and volunteers try to free people trapped under the wreckage of a collapsed fly-over bridge in Kolkata, capital of eastern Indian state West Bengal, on Thursday. — AFP Photo

KOLKATA - Hundreds of emergency workers in India battled yesterday night to rescue dozens of people still trapped after a flyover collapsed onto a busy street, killing at least 22 people and injuring nearly 100.

The flyover was under construction when a 100-metre section collapsed suddenly onto a crowded street in the eastern city of Kolkata aroundlunchtime, crushing pedestrians, cars and other vehicles under huge concrete slabs and metal.

"The death toll has risen to 22," said Javed Ahmed Khan, disaster management minister for the state of West Bengal.

Anil Shekhawat, a spokesman for the National Disaster Response Force (NDRF), said seventeen survivors out of 92 rescued were still undergoing treatment at hospital.

Most suffered multiple fractures and were in a critical condition, Shekhawat added, saying that the death toll was expected to rise, with an unknown number of people still trapped under the wreckage.

Specialist rescue teams armed with concrete and metal cutters, drilling machines, sensors to detect life and sniffer dogs were sifting through the rubble.

Anurag Gupta, a spokesman for the National Disaster Management Authority, said hundreds of rescuers would work through the night to rescue the trapped victims.

"Four hundred men from NDRF and 300 Indian army men along with hundreds of police and local officials are at the spot," Gupta said.

Authorities sealed off the accident site to members of the public, who in the initial hours were seen trying to pull away concrete slabs with their bare hands.

Workers struggled to get cranes and other large machinery through the narrow streets of Burrabazar, one of the oldest and most congested parts of the city, where locals desperately waited for news of missing loved ones.

"Everything is finished," screamed Parbati Mondal, whose fruit-seller husband had not been seen since the accident.

An injured builder said at the scene that he had been working on the structure before it collapsed and had seen bolts come out of the metal girders.

"We were cementing two iron girders for the pillars, but the girders couldn’t take the weight of the cement," said 30-year-old Milan Sheikh before being taken away to hospital.

"The bolts started coming out this morning and then the flyover came crashing down."

Construction on the two-kilometre-long flyover began in 2009 and was supposed to be completed within 18 months but has suffered a series of hold-ups.

The disaster is the latest in a string of deadly construction accidents in India, where enforcement of safety rules is weak and substandard materials are often used. – AFP