The deceased was Mustaqim, 17, son of Surjot Ali of Charshakchura village and an autorickshaw driver and sound system operator.
Khairul Bashar, Officer-in-Charge of Pagla police station, said the victim went to Waz Mahfil (a religious event) at Ansar Nagar Madrasa to work as a loudspeaker operator.
Sajal locked into an altercation with Mustakim when he went to a fair adjacent to the event venue.
At one stage of the altercation, Sajal stabbed Mustakim's neck, shoulder and hand with a knife, leaving him critically injured.
Later, locals rescued him and rushed to Gafargaon Upazila Health Complex where on duty doctors declared him dead.
Later, the body was sent to Mymensingh Medical College Hospital morgue for autopsy.