The incident occurred around 10.30 a.m. near Ghoramara island of South 24 Parganas district. The trawler was sailing to Kakdwip from Hijli Sarif in East Midnapore district, Additional Director General of police (Law and Order) Surojit Kar Purokayastha said. There were over 100 people on board.
"Eighteen bodies have been fished out so far. Search operation has been called off for the day due to darkness and will resume tomorrow," Chief Secretary Samar Ghosh told reporters at state secretariat - Writers' Building.
However, South 24 Parganas district magistrate N.S. Nigam claimed the place where the the trawler capsized was under the jurisdiction of the East Midnapore district administration.
"The accident occurred due to high water current. We have sent several rescue trawlers to the spot," Nigam said, adding that 32 of the injured have been admitted to Kakdwip Subdivision hospital. "All the victims were locals and some of those rescued have returned to their villages," he said.
The zilla parishad president of neighbouring East Midnapore district Ranjit Mondal claimed the casualty figure could be as high as 40.
State Sundarban Affairs Minister Kanti Ganguly said around 50 people had been rescued.
Senior administration and police officers held a high-level meeting and decided to ask for divers from the navy for rescue operations.
"Since there are no divers in Kolkata, the Eastern Naval Command at Visakhapatnam has been contacted," defence ministry spokesperson Wing Commander Mahesh Upasani told IANS here.