One person died and at least 21 people were injured after a portion of the Majerhat bridge in Kolkata collapsed on Tuesday. The structure collapsed onto railway tracks in Alipore in South Kolkata, the Hindustan Times reported.

Many vehicles were crushed under the debris. The bridge is located in a crowded part of the city.

The deceased has been identified as a male.

Personnel from the Kolkata Police, State Disaster Management Squad, Fire and Emergency Services, Civil Defence and the National Disaster Response Force worked in tandem to conduct rescue operations.

Kolkata Mayor Sovan Chatterjee said officials were trying to ascertain if people are still trapped beneath the debris, Reuters reported.

Chief Minister Mamata Banerjee said the police were investigating the matter and that she was monitoring the situation from Darjeeling, where she is currently on a visit. “I have asked the police to provide details,” Banerjee told the Hindustan Times. Banerjee said she was trying her best to return to the city at the earliest to take stock of the situation but that flights were unavailable.

Home Minister Rajnath Singh spoke to Banerjee and assured her of the Centre’s support if needed, ANI reported.

Trinamool Congress MP Derek O’Brien took to Twitter to share updates on the rescue operation. “Rescue teams, disaster management teams, police personnel and fire fighters are at the site,” O’ Brien tweeted. “It is difficult to gauge the enormity of tragedy.”

Army personnel also helped in the rescue efforts, NDTV reported. The Indian Army said that though its personnel were not called in, an Army field hospital detachment was sent as the area is very close to its Fort William base.

Kolkata Traffic Police tweeted updates on traffic diversions following the incident. “DH Road towards Maherjat Bridge is closed to traffic from NR Avenue,” the traffic police tweeted. “DH road has been closed from CGR road and Ekbalpore crossing. Alipore road is closed to traffic from Judges Court road.”

In March 2016, the under-construction Vivekananda flyover in the city collapsed leading to the death of 27 people. On August 11, a portion of a four-lane under-construction flyover collapsed near Siliguri.

In August, The Telegraph had reported the Public Works Department was repairing the potholed-ridden thoroughfare

Prime Minister Narendra Modi expressed his solidarity with the victims. “The collapse of a part of a bridge in Kolkata is deeply unfortunate,” Modi tweeted. “My thoughts are with the families of the victims. I pray that those who are injured recover at the earliest.”

West Bengal Governor Keshari Nath Tripathi said an investigation into the bridge’s maintenance was needed. “There was a report on [the presence of] a pit here for quite some time, I do not know whether the Public Works Department noted it,” Tripathi told ANI. The Public Works Department and the railway administration had the responsibility to maintain it.”

Bharatiya Janata Party National President Amit Shah asked party workers to assist in the rescue operations.

BJP leader Mukul Roy said the Trinamool Congress-led state government is responsible for the collapse. “They are saying the beautification of the city is underway, but repair work of old constructions is not on her [Banerjee’s] mind.”

Train services suspended

Train services on the Kolkata Circular Railway and Sealdah-Budge Budge line have been suspended as precautionary measure, Eastern Railway spokesperson RN Mahapatra said according to PTI. A portion of the bridge collapsed close to the Kolkata Circular Railway line and damaged a signal post, Mahapatra said.