Members of Rapid Action Battalion (RAB) cordoned off a house in Char Alatuli union of Chapainawabganj Sadar upazila from early Tuesday suspecting it a militant den.
Col Mahabub ALam, commanding officer of RAB-5, said that on secret information a team of RAB cordoned off the abandoned house owned by Rafiqul Islamat the Ward No. 5 of the union and asked the militants in the house to surrender.
At one stage, the militants opened fire and threw grenade to the elite forces which prompted them to retaliate back.
The elite force will take next steps after arrival of its bomb specialist unit, said the RAB official.
Local sources said Rafiqul Islam, who has been suffering from cancer, did not stay in the house for long time.
They also heard the sounds of bullets and explosions around 4:30am.