Apart from this, another accused, Ibrahim Hossain, 26, was arrested from Kushtia on the same day.
Pabna additional police superintendent Masud Alam confirmed the matter to Prothom Alo, adding that they were arrested on a tip-off from Arambaria area and Kushtia respectively. They were sent to the court in the afternoon.
Earlier, the Rapid Action Battalion (RAB) arrested two, including the prime accused Kamal Uddin, Ward No 1 councilor of Ishwardi municipality in Pabna.
On 4 January, a rickshaw puller, Mamun Hossain, was killed and two others injured in a shoot-out at Ishwardi upazila of Pabna. The incident took place at 9:00pm at West Tengri Koroitala area of Ishwardi municipality sadar.
Witnesses said the casualties took place in the firing by local Jubo League leader Anwar Hossain.
The slain rickshaw puller, son of Manik Hossain, is a resident of Piyarakhali at Ishwardi municipality. The two other bullet injured are Rocky Hossain, 26 and Suman Hossain, 28.