Metropolitan Magistrate Sadbir Yasir Ahsan Chowdhury passed the order on Tuesday.
Police took them to court and sought a 10-day remand to question them in the case.
All are students of BUET.
A resident of Sher-e-Bangla Hall, Abrar was bludgeoned to death on Sunday. His classmates alleged that BCL men beat him to death suspecting his links to Islami Chhatra Shibir, the student wing of the Jamaat-e-Islami.
Police retrieved the body from the first-floor stairway of the dormitory. Abrar's father Barkatullah subsequently started a case against 19 people over the incident.