The boat carrying over 50 people returning from a fair at Kalna in Burdwan to Shantipur sank last night, Burdwan Superintendent of Police Gaurab Sharma said.
While many people swam to safety, five persons, including two to three children went missing, he said, adding rescuers of the Disaster Management Group, civil defence and private divers were pressed into service to find them.
Meanwhile, alleging that the administration delayed in initiating the rescue operation, a group of people from Shantipur torched several boats, trawlers and launches anchored on the bank today, police said.
They also set on fire the office of the ferry-service and pelted stones at policemen injuring two of them, they said.
The policemen fired teargas shells, rubber bullets to disperse the violent protesters, Nadia SP Sheesh Ram Jhajharia said when contacted.
"The situation is normal now ... It's under control. Nobody is injured in police action," Jhajharia said.