Images from the scene show a 100-foot section of the bridge pancaked on top of rail tracks in the Kolkata neighborhood of Alipore. Several vehicles, including motorbikes and one bus can be scene in the wreckage.
Eyewitnesses told local media outlets that the collapse took place at around 4:45 p.m. local time. "We heard a noise and came out to see what happened… we realized a part of the Majerhat bridge collapsed," an eyewitness told ANI News.
With officials having suggested that many others might be trapped in the rubble, West Bengal Chief Minister Mamata Banerjee said Tuesday that there might be additional casualties, between three and four, underneath the 40-year-old bridge, as the area was known as a slum, the Times of India reported.
Although the matter is being handled as a search and rescue mission presently, officials are calling for an investigation into the cause of the incident. It has been suggested by opposition parties in West Bengal that the collapse was the result of poor bridge maintenance.
"It is really unfortunate that the bridge collapsed, but the fact is that the state government is solely responsible for the bridge collapse," Mukul Roy, leader of India's Bharatiya Janata Party, said in a statement. "The issue of repair of the old bridges is not at all in the agenda of TMC [Trinamool Congress] government."
Minister of Municipality Affairs of West Bengal Firhad Hakim told ANI that a "fast-track investigation" would be launched in order to pinpoint the cause of the disaster.
A total of five teams from the National Disaster Response Force and members of the Central Armed Police Force have been sent to the area to offer support in ongoing rescue operations, according to the Times.
Social media reports have also indicated that cranes have been brought onto the site as officials continue to make their way through the wreckage.
Reacting to the incident, Indian Prime Minister Narendra Modi issued a statement on Twitter, saying, "The collapse of a part of a bridge in Kolkata is deeply unfortunate. My thoughts are with the families of the victims. I pray that those who are injured recover at the earliest."
Two years ago another section of a bridge collapsed in Kolkata. An official report later indicated that the cause was due to bad design and poor quality of materials used in its construction, AP reported. In that incident, 26 people were killed and dozens of others were injured.
The latest incident comes more than two weeks after the Morandi motorway bridge collapsed in Genoa, Italy, in late August. According to local media reports, nine people were taken to a hospital, eight whom were deemed in serious condition at the time. At least 43 were killed.