A half-dozen vehicles, including a bus, fell with the broken section of concrete, about 100 feet (30 meters) long, in Kolkata’s Majerhat neighborhood.
News reports said more than 20 people were taken to area hospitals. At least one person died, according to an official at the city’s Seth Sukhlal Karnani Memorial Hospital who spoke on condition of anonymity because he wasn’t authorized to speak publicly.
Officials were unsure how many people might be trapped beneath the concrete, and police and firefighters were working into the night, using cutting tools to clear the wreckage.
West Bengal Chief Minister Mamata Banerjee told reporters that several transportation workers may have been in a small office under the overpass when the collapse occurred.
It was the second major road collapse in Kolkata in recent years. In 2016, a section of an unfinished overpass cutting through Kolkata collapsed, killing 26 people and leaving dozens injured.
WATCH BELOW: Overpass buckles in Kolkata in 2016
An official report later blamed that accident on bad design and poor-quality materials.