Only one of the five attended a madrassa, the son of a labourer who has been named as Khairul Islam Payel.

Some analysts attribute the rise in extremism in the South Asia region to the preachings of radical Saudi-trained clerics in madrassas, religious seminaries that are often the only way for poorer families to give their children an education.

https://au.news.yahoo.com/world/a/31982808/bangladeshi-rich-kids-who-grew-up-to-be-jihadists/#page1