The accident is the first major mishap on railways property after Mamata Banerjee recently took charge as the railways minister.

Howrah Superintendent of Police Neeraj Kumar Singh, who coordinated the rescue operations with railways officials, said the reasons behind the accident were being investigated.

“At the moment, all we know is that the minibus (WB-11-2154) plying on the Sankrail-Howrah route broke the bridge’s railing directly above platform no 12 and fell on its roof at 3.40 pm. It could have been due to a mechanical failure or racing by buses. The injured have been moved to Howrah General Hospital and the Railways’ Orthopaedic hospital,” Singh said.

Senior railways officials, including DRM M Jamshed, said the railways rescue infrastructure, including an accident relief train, has been deployed.

“We had to turn the bus over onto its wheels and cut a part of its body before pulling out the casualties. We expect the bus to be removed from the tracks at the earliest. Train services haven’t been disrupted,” he said.

Officials said the last train to pass through platform 12 was the Malda Inter-city, which departed at 3.25 pm.

According to an eyewitness, Sheikh Moid Islam (26), who was waiting on Bankim Setu for a bus, the ill-fated vehicle came at high speed and lost control.

“It was raining hard. I saw the bus run over the pavement and break through the railing. Locals began rescuing victims using taxis to take them to hospital. I took the bus driver and another victim to hospital,” he said.

As rescue workers used blowtorches to cut the smashed bus into pieces, railways personnel used tin sheets for a temporary repair job on the broken bridge railing.

Meanwhile, Trinamool Congress leaders Partha Chatterjee and Arup Roy arrived on the spot as Mamata’s emissaries to take stock of the situation.