Law enforcers detained three alleged extremists, including two siblings, from a suspected hideout they cordoned off at village Dangapara of Tanore upazila in Rajshahi early Monday.
The three alleged extremists are -- Israfil Alam, 26, his elder brother Ibrahim, 34, and son-in-law Rabiul Islam,35, of the village Dangapara.
Nine others, including women and children, have been taken to the police station.
The building is still cordoned off. Police suspect there may still be powerful explosives inside.
Moazzem Hossain Bhuiya, superintendent of police in Rajshahi, said that a joint team of police and detective branch of police cordoned off the house at the village suspecting it an extremist den and arrested the suspects around 2:30am on Monday.
The team recovered suicidal vests and a large number of pistols and bullets from the house and suspected there were more explosives inside the house, said the police official.
The police official added that they had requested for a bomb disposal unit from Dhaka.