The mishap at Mumbra railway station on Monday morning that killed four and injured nine occurred as the passengers standing on the footboard of two suburban trains brushed against each other, causing thirteen to fall, a Thane railway police station official said.

The incident took place at kilometre marker 40/304 to 306 (signifying distance of 40 kilometres from Central Railway headquarters Chhatrapati Shivaji Maharaj Terminus) at 9:01am between platforms number three and four of Mumbra station, a release from Thane railway police station said.

"The trains involved were the CSMT-Karjat Down Fast local and the Kasara-CSMT Up Fast local. As the two trains passed each other at high speed, passengers hanging out of the coaches on footboards collided, causing thirteen of them to fall onto the tracks and nearby areas," the release said.

Emergency teams from Thane Railway Police (GRP), Railway Protection Force (RPF) as well as passengers in the vicinity responded to provide relief and rushed the victims to Chhatrapati Shivaji Maharaj Hospital in Kalwa, it said.

Two severely injured passengers were shifted to Jupiter Hospital for brain surgery and other advanced medical treatment, while the bodies of the four deceased were sent for post mortem, the police official said.

Seven injured passengers continue to be treated at CSM Hospital in Kalwa, the government railway police release added.

"The Thane Railway Police is investigating the incident and taking appropriate legal action," the GRP stated in its release.

Earlier, an eyewitness to the horrific suburban railway mishap said the chain of events began after someone in the coach ahead of his either fell after hitting a wall or "something hit our compartment".

This eyewitness, a Bhiwandi resident, had boarded the Kasara-CSMT train at Kalyan station.

"The incident happened when the train reached Mumbra station. Someone from the coach ahead of ours fell off after hitting a wall or something hit our coach. At that time, three-four people from our coach fell down and some from other coaches also fell. I think 7-8 persons lost balance and fell onto the tracks," he said.

He said his friend Rehan Shaikh (26), who was coming from Kalyan to Thane, was injured in the accident.

In the morning, the passenger flow in Mumbai's suburban network is towards the south of the metropolis where a majority of the offices are located. The flow reverses in the evening as people start leaving for home towards Thane and beyond on the Central Railway network and Andheri and beyond on Western Railway.

The morning and evening rush hours in the network are among the densest in the world.

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