The Belfast Institute of Further and Higher Education had to close for a day when a gang threatened students after four nights of rioting in the city.
The gang burst into the Tower Street section of the college, asking students if they were Catholics and threatening to shoot them if they were. Some were told to recite the alphabet, so the gang could hear how they pronounced the letter "h" - to show whether they were Catholics.
When the police arrived, the gang ran off and staff drove students home.
Employment and learning minister Carmel Hanna demanded an urgent report.