They were arrested at Islamia Madrasa centre on Sunday, Barisal Superintendent of Police SM Aktaruzzaman told bdnews24.com.
They have been identified as exam centre Secretary Md Bashir Uddin, 47, and teachers Md Nuruzzaman, 45, Md Jasimuddin, 45, Mehedi Hasan, 40, Abu Hanif, 30, and Abul Kalam, 45.
The SP said police raided the centre on a tip-off that a syndicate was regularly selling question papers with answers to the candidates by opening the sealed envelopes of question papers half an hour ago before the exams.
He said police were initiating a case against them under the Public Examinations (Offences) Act.
The education ministry has been facing widespread criticism following the revelation of question paper leak in ongoing SSC and equivalents examinations in bdnews24.com investigations. Dakhil is the examination for madrasa students equivalent to SSC.