Police detained three members of a family and cordoned off their house, suspecting it to be a militant den in Narayanganj's Fatullah on Monday.
The detainees are Fariduddin Rumi, 27, a teacher of Ahsanullah University of Science and Technology, his wife Jannatul Foara Anu, 27, an official of Agrani Bank and his brother Jamaluddin Rafiq, 23, a mechanical engineer from Khulna University of Engineering and Technology (KUET).
Fariduddin Rumi and Jamaluddin Rafiq are the sons of Bangladesh Bank's former deputy general manager Joynal Abedin.
The members of the Counter Terrorism Unit with the help of local police have been conducting a raid on the house since 8:15am acting on a tip-off that militants were hiding there, said police.
Inspector of Detective Branch of police, Sazzad Ruman, said that a number of police including SWAT (Special Weapon And Tactics) members cordoned off the house.