The bridge was being built to bring railway connectivity to Aizawl, the capital of Mizoram. There were 40 construction workers on the bridge at the time of the collapse.
"Seventeen bodies have been recovered from the debris so far...many others are still missing," a police officer said.
The cause of the collapse is not yet known. Sabyasachi De, chief public relations officer of Northeast Frontier Railway (NFR), said: "We are yet to ascertain the reason behind the accident and how many people actually were on it when it occurred."
The bridge that collapsed was part of an Indian Railways project to connect all state capitals in the northeast region. It has been under construction for some years now.
The collapse is a major tragedy and the authorities are working to rescue the trapped workers. The families of the victims have been informed and are being provided with assistance.
The government has ordered an investigation into the collapse. (ILKHA)