Police on Monday arrested nine persons, including four from the Oreva group that was managing the Morbi suspension bridge, and filed a case against firms tasked with maintenance and operation of the British era structure which collapsed, killing 134 people.

Video footage emerged of the moments before Sunday' evening's deadly collapse, showing the bridge snapping in a few seconds, taking down scores of visitors seen walking on the swaying British-era structure which reopened five days ago after extensive repair but sans a fitness certificate.

"Nine people have been arrested in the Morbi bridge collapse case. They include two managers and two ticket booking clerks of Oreva group that was managing the bridge," Rajkot Range IG Ashok Yadav said, informing media of the criminal investigation into the tragedy that has shocked the country.

The death toll in the bridge collapse has mounted to 134, he said.

A day after the bridge crammed with visitors came crashing down, sending people tumbling into the river below, rescue operation continued as authorities looked for survivors.

Gujarat Chief Minister Bhupendra Patel and Minister of State for Home Harsh Sanghavi remained in Morbi during the night to oversee the rescue operation being conducted by multiple agencies.

The more than a century-old bridge on the Machchhu river in Morbi, located around 300 km from the state capital Gandhinagar, collapsed around 6.30 pm on Sunday.

The state information department said five teams of the National Disaster Response Force (NDRF), six platoons of the State Disaster Response Force (SDRF), a team of the Air Force, two columns of the Army, and two teams of the Indian Navy apart from local rescue teams were involved in the operation.

Sanghavi told reporters the state government has formed a committee to conduct a probe into the bridge collapse.

Police have registered an FIR (first information report) on charges of culpable homicide not amounting to murder and attempt to commit culpable homicide against agencies given the task of maintenance and operation of the bridge.

In the FIR lodged at the Morbi 'B' division police station on Sunday night, police have shown "agencies responsible for maintenance and management of the hanging bridge" as the main accused.

The FIR, lodged by 'B' division police inspector Prakash Dekivadia, stated that the bridge over the Machchhu river was not in use for nearly eight months as the local administration had roped in a "private agency" for its maintenance.

After completion of the maintenance, the agency opened the bridge for the public on October 26, the FIR said.

As per the FIR, the incident took place because of the "callous approach" of the agency people.

The FIR further stated that persons concerned or agencies did not pay attention to the quality of maintenance as well as repair work of the bridge.

The bridge was opened for tourists by the agency despite knowing that their "callous approach" in the maintenance and management of the bridge may lead to human deaths, the FIR stated.

"We have lodged an FIR and are trying to establish contact with the Oreva company's staff who were on duty at the bridge yesterday," SP Rahul Tripathi said.

Prime Minister Narendra Modi, who is on a tour of poll-bound Gujarat, remembered those who died in the tragedy.

He paid tributes to India's first home minister Sardar Vallabhbhai Patel on his birth anniversary at the Statue of Unity at Kevadia in Narmada district.

"I am in Kevadia, but my heart goes out to those who died in the Morbi Bridge collapse tragedy," the PM said as he got emotional.

Troupes from across country had come to Kevadia to perform traditional dances, but the programme was cancelled due to the present circumstances, he said.

Eyewitnesses said there were several women and children on the "hanging bridge" when it snapped, plunging them into the water below.

Apart from locals, people from nearby cities and villages had also come to the bridge on a holiday when it collapsed.

Due to the Diwali vacation and being a Sunday, there was a rush of tourists on the bridge, a major tourist attraction.

Before the tragedy occurred, some people were seen jumping on the bridge and pulling its big wires, an eyewitness said, adding that the bridge may have collapsed due to the "huge crowd" on it.

People fell over each other when the bridge collapsed, he said. Several of the victims were seen hanging by the edge of the bridge to prevent themselves from slipping into the river.

After the collapse, all that remained of the bridge was part of the metal carriageway hanging down from one end into the river water, its thick cables snapped in places.

At the local hospital, people formed a human chain to hold back crowds and keep the road clear for ambulances which brought those rescued.

Oreva had carried out the repair work of the bridge for nearly seven months before it was reopened for the public on the Gujarati New Year day on October 26.

The bridge was reopened after a private inaugural event and was yet to receive the municipality's "fitness certificate," a civic official said.

Following the accident, Modi cancelled his road show scheduled to be held in Ahmedabad on Monday ahead of the state Assembly polls.