Sujon was the fifth member of the family to succumb to burn injuries
The raid was conducted around 10:30pm on Wednesday, the district's Additional Superintendent of Police Abdullah Al Mamun told bdnews24.com.
He said RAB and police conducted the operation following a tip-off.
The three detained students are roommates.
A number of jihadi books were found in the room, the police official said.
The detained students were being questioned at the office of the superintendent of police, he added.