A class X student was beaten to death, while his classmate was left injured in Bokchora Bypass area of Satkhira around 10:00pm on Tuesday.
Police have arrested one person in this connection.
The dead, Sakib Hossain, 16, only son of Police constable Nazrul Islam of Palashpol Boubazar area, was a student of Police Line Secondary School. The injured, Rashedul Islam, is a son of retired policeman Abdul Aziz of Rasulpur area in the town.
Nazrul filed a case against five people who were allegedly involved in the attack, while only one of them was arrested.
The arrestee, Ronny Hossain, aged around 19, is from Kamalnagar Colony in Satkhira and is a student of a local college in the area.
Police said the reason behind the attack was a sudden altercation between the attackers and the victims.
Rashedul, who is undergoing treatment at Satkhira Sadar Hospital, said he and his classmates, Sakib and Omi, went to listen to waz mahfil at Bokchora Madrasa earlier on the day of the incident. There, Sakib had an altercation over a trifling matter with Ronny and Abdul Quader, which was later settled.
Rashedul said that later that night he and his friends were on their way home, after his father had called him around 9:30pm. When they reached Bokchar Bypass Road area, 20 to 25 people, led by Quader and Ronny, attacked them with sticks.
When Rashedul tried to rescue Sakib, he was beaten as well. At one stage Sakib fell, and the attackers left the spot leaving Sakib and Rashedul seriously injured.
Locals took Sakib and Rashedul to Satkhira Sadar Hospital.
Dr Porimol Kumar Biswas at the emergency unit of the hospital said the two boys were brought to the hospital around 10:45pm. Sakib succumbed to his injuries and died before they reached the hospital.
Meanwhile, Rashedul is undergoing treatment and his condition was improving.
Sakib's father, currently posted at Soroshkati police camp in Kolaroa upazila, said his son was innocent and demanded immediate trial of the killers.
Satkhira Sadar Police Station Officer-in-Charge (OC) Faruq Ahmed said six people were taken in custody for interrogation. One of them was released, while the others will remain in custody for further questioning.