Another man named Sagor Pradania, 25, sustained injuries from the lightning and is currently being treated at Dhaka Medical College Hospital.
The incident occurred around 4:00am today at Anandabazar point of Padma river in Vedarganj upazila.
According to locals a fishing boat was struck by lightning in the early hours of the morning.
Later, fishermen of other boats found three of the fishermen in that boat dead and sent the critically injured Sagor to hospital after rescuing, said ward-4 UP member Moslem Uddin.
Officer in charge of Sakhipur police station Md Obaidul Haque said the deceased were handed over to their families who completed their last rites.