New Delhi - At least 16 bodies have been recovered from the debris of a flyover that collapsed in the Indian temple town of Varanasi on Tuesday.

Several people were feared trapped, and the death toll could rise, Varanasi district magistrate YN Mishra said. Four people had been rescued so far, Mishra added.

The flyover was under construction and part of it collapsed during busy evening traffic, with big slabs of concrete crushing the vehicles travelling on the road below, an official at the Varanasi police control room said.

Six teams belonging to the National Disaster Response Force were at the site helping with rescue operations, local police officer Dinesh Singh said.

"Extremely saddened by the loss of lives due to the collapse of an under-construction flyover in Varanasi. I pray that the injured recover soon," Prime Minister Narendra Modi posted on Twitter.