MORBI, India — Police in western India arrested nine people Monday as they investigated the collapse of a newly repaired 143-year-old suspension bridge in one of the country’s worst accidents in years, officials said.

The collapse Sunday in Gujarat state plunged hundreds of people into a river, killing at least 134.

As families mourned the dead, attention turned to why the pedestrian bridge, built during British colonialism in the late 1800s and touted by the state’s tourism website as an “artistic and technological marvel,” collapsed and who might be responsible.

The bridge had reopened four days earlier.

Inspector-General Ashok Yadav said police have formed a special investigative team, and that those arrested include managers of the bridge’s operator, Oreva Group, and its staff.

“We won’t let the guilty get away, we won’t spare anyone,” Yadav said.

Gujarat authorities opened a case against Oreva for suspected culpable homicide, attempted culpable homicide and other violations.

In March, the Morbi town government awarded a 15-year contract to maintain and manage the bridge to Oreva, a group of companies known mainly for making clocks, mosquito zappers and electric bikes. The same month, Oreva closed the bridge, which spans a wide section of the Machchu River, for repairs.

The bridge has been repaired several times in the past and many of its original parts have been replaced over the years.

It was reopened nearly seven months later, on Oct. 26, the first day of the Gujarati New Year, which coincides with the Hindu festival season, and the attraction drew hundreds of sightseers.

Authorities said the structure collapsed under the weight of hundreds of people. A security video of the disaster showed it shaking violently and people trying to hold on to its cables and metal fencing before the aluminum walkway gave way and crashed into the river.

The bridge split in the middle with its walkway hanging down, its cables snapped.

Police said 134 people were confirmed dead, and many others were admitted to hospitals in critical condition. Emergency responders and rescuers worked overnight and Monday to search for survivors.

At least 177 survivors were pulled from the river, said Jigar Khunt, an information department official in Gujarat.

It was unclear how many people were on the bridge when it collapsed, but survivors said it was so densely packed that people were unable to quickly escape when its cables began to snap.

Gujarat is the home state of Prime Minister Narendra Modi, who was visiting the state at the time of the accident. He said he was “deeply saddened by the tragedy” and his office announced compensation for families of the dead.

“Rarely in my life, would I have experienced such pain,” Modi said during a public event Monday.