A woman was slaughtered allegedly by his mentally challenged son at Khararchar area of Dhamrai upazila in the city early Monday.
The deceased was identified as Jamina Khatun, 55, wife of Abdul Baser.
Sheikh Rezaul Haque Dipu, officer-in-charge of Dhamrai Police Station, said that the mentally challenged Raihan slaughtered his mother Jamina while she was sleeping, reports UNB.
As his father and elder brother came to save Jamina, he also hacked them, leaving critically injured.
The injured father and son were admitted at Savar Enam Medical College Hospital.
Locals handed Raihan over to police.