The eldest son of Jamaat-e-Islami leader and former MP Major (retd) Mohammad Akhtaruzzaman Ranjan was stabbed by unidentified assailants in Katiadi upazila of Kishoreganj on Wednesday night.
The victim, Shahriar Zaman, 40, was attacked at Gachihata Bazar around 8:00pm.
Locals rescued him and took him to Katiadi Upazila Health Complex, where he received initial treatment.
He was later being taken to Jahurul Islam Medical College Hospital in Bajitpur for better treatment.
Akhtaruzzaman confirmed the incident over the phone around 9:45pm, saying his son had gone to Gachihata Bazar when the assailants suddenly attacked him.
Katiadi Police Station Officer-in-Charge Mohammad Rafiqul Islam said police had been sent to the scene after receiving information about the incident.
The identities of those involved and the motive behind the attack were not immediately known.
Police said legal action would be taken following an investigation if a complaint was filed.