The arrests of the members of the banned militant outfit Jama'atul Mujahideen Bangladesh (JMB) was made at Jamaitul Cadet Madrasa around 5am on Tuesday, says Sirajganj DB Sub-Inspector Rawshan Ali.
During the drive, the DB team discovered ten crude bombs, 1kg gun powder, 500 pieces of splinters, bomb-making materials and a large stock of books containing jihadi contents from their possession.
The arrested are Md Joynal Abedin, 55, president of Sirajganj unit JMB and Md Abu Bakkar Siddique, 50, cashier of the unit, while the rest two are Joynal's sons Borhan Uddin, 28, and Imran Ali, 26. All of them are residents of the district.
Rawshan Ali said the four had long been running the activities of the banned outfit secretly at the madrasa and they confessed it during the initial questioning.
The detectives had information that the militants finally planned to conduct a big destructive operation in the district.
The government banned JMB on February 23, 2005 for carrying out series of attacks across the country.