Sanjib Kumar, president of the organisation, said the programme was inaugurated on Friday afternoon, marking the organisation's 18th anniversary. They resumed the cultural programme after a discussion.
"Suddenly, a group of people attacked the venue. Our musical instruments, along with nearly 50 chairs at the venue, were vandalized," he said.
The organisation's sound operator Suman and Baul singer Harun were among the injured, he added.
Officer in charge of Sirajganj Sadar police station Md Humayun Kabir said they visited the spot on information.