The Rapid Action Battalion (RAB) on Saturday detained one of its members along with four people in connection with extortion in Narayanganj.The detainees are-Constable of RAB-13 Humayun Kabir and Shahida, 45, Md Amzad, 32, Md Mahbub Islam, 30 and Md Hasanuzzaman, 24. RAB-11 commander Anwar Latif Khan said that, they were caught while trying to extort Tk 100,000 from one Md Mohsin.Humayun had already taken Tk 350,000 from Mohsin and was supposed to receive another Tk 100,000 today, he added.