At least 10 people were killed and 150 were feared trapped when a flyoverunder construction collapsed in the Indian city of Kolkata, police said.

Firefighters and residents were trying with their bare hands to rescue those trapped under the wreckage of the bridge.

A Reuters witness said paramedics at the scene had worked to free people from a minibus taxi that was crushed in the collapse.

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

There was reportedly little sign of a coordinated rescue operation, with access for heavy lifting equipment restricted by the proximity of buildings on either side of the flyover and heavy traffic.

The flyover has been under construction since 2009 and has missed several deadlines for completion. Construction projects in India have long been plagued by lax safety standards.