Jane Onyanga-Omara

USA TODAY

At least 21 people died and dozens were injured Thursday after an overpass that was under construction collapsed in the eastern Indian city of Kolkata.

The incident happened in a busy part of the Girish Park area.

More than 70 injured were admitted to two hospitals in Kolkata, the capital of West Bengal state, hospital officials said, according to the Associated Press. At least 21 were dead, the AP reported. The Times of India put the death toll at 17.

The collapse occurred around noon at a busy intersection near Burrabazar, the trading center of one of the most congested areas in the city, The Times says.

Up to 100 people were feared to be trapped under the debris and cars, trucks and rickshaws could be seen under the rubble, the Times of India reported. A rescue operation was underway.

"We heard a noise and got scared. Yesterday (the bridge) was welded. The bridge collapsed. I think at least 150 people are under the debris," witness Ramesh Kejriwal told the Asian News International (ANI) news agency.

Yogesh Sharma was sitting at a small roadside tea stand with friends when the overpass, which spanned nearly the width of the city street and was designed to ease traffic through the densely crowded neighborhood, “came down with a huge crashing sound.”

“I left my cup of tea and ran,” said Sharma, a 23-year-old resident of the Bara Bazaar neighborhood, the Associated Press reported. “I was crying at the spot.”

Smashed yellow taxis, destroyed rickshaws and the bloody legs of trapped people jutted from the collapsed girders and concrete slabs.

The fallen sections of the overpass totaled perhaps 100 yards; many other parts were still standing. Mamta Banerjee, the top elected official of West Bengal state, said a private builder had missed several deadlines for completing the construction.

The overpass was supposed to have been completed three years ago, but construction was delayed six times, the Times of India reported. Building collapses are common in India, where regulations can be poorly enforced and some builders use substandard materials.

Contributing: Doug Stanglin