The incident occurred at around 7:00pm in a house at Khoshalpur Putal village in Kakilakura union of the upazila.
Hasan Nahid Chowdhury, Sherpur superintendent of police (SP), said that Mintu Mia, wearing a burqa, attacked his father-in-law's house over a dispute with his wife Monira Begum.
“Mintu slit three people’s throats and hacked another three before he fled the scene,” he said.
Locals took the injured to Bakshiganj upazila hospital in Jamalpur where three were declared dead. As the condition of the remaining three deteriorated, they were sent to Mymensingh Medical College Hospital for advanced treatment.
Police could not detain the accused but legal actions were underway, SP Nahid added.