The deceased was identified as Nazrul Islam Munna, 21, a second-year student (Hons) at Gowainghat Government College and son of Md Rafiqul Islam of Nandirgaon in Gowainghat upazila.
Locals said the incident took place around 8:30pm when Munna was crossing Kazi Elias Lane of the city.
Noticing that some footpath vendors were assaulting a customer, Munna went there and protested but received fierce response from them. Some of them, at one stage, stabbed them before fleeing the spot.
Munna was first taken to Sylhet MAG Osmani Medical College Hospital where doctors suggested that he be shifted to Dhaka. Later, he succumbed to his injuries in early hours of Friday while being taken to Dhaka.
Md Selim Mia, officer-in-charge of Kotwali Police Station, said they arrested a man in connection with the killing as the deceased’s father filed a case.