By Manveena Suri, Swati Gupta and Rhea Mogul, New Delhi, Jan 14 (CNN): At least nine people were killed and 36 others injured after a passenger train derailed in India's West Bengal state late Thursday, according to the railway operator.

Indian Railways spokesperson Rajesh Bajpai said four out of 12 carriages on the interstate express train veered off the track in the state's Jalpaiguri district.

"It looks like there are no more people trapped in the carriages," said another railway spokesperson, Gurmeet Kaur. Workers were restoring the track to allow other trains to pass, he added.

Initial assessments suggest there was a crack in the tracks, CNN affiliate News-18 reported, citing local authorities.

West Bengal's Chief Minister Mamata Banerjee said she was "deeply concerned to hear about the tragic accident."

"Those injured will receive medical attention, as early as possible," she wrote on Twitter on Thursday.

Indian Prime Minister Narendra Modi said on Twitter Thursday that his "thoughts are with the bereaved families," and he wished the injured a speedy recovery.

India's extensive rail network suffers from ageing infrastructure and poor maintenance -- factors that are often responsible for accidents.

In 2020, nearly 12,000 people were killed in more than 13,000 train accidents across the country, according to a report last year by the National Crime Records Bureau (NCRB).

One of the most deadly incidents of recent years occurred in November 2016, when more than 140 people were killed after several train cars derailed in northern Uttar Pradesh state.

The following November, at least 39 people died and 50 others were seriously injured in a train derailment in the southern state of Andhra Pradesh.