Police said the trouble begun in the morning when some Bangalee students prevented tribal students from taking ganja in a room of the college.

The clash later spread in the adjacent areas, leaving 20 people injured.

Bangalee Chhatra Parisad leaders Shahadat Hossain, Saidur Rahman, Imon and Dipu are among the injured.

Two of the injured were admitted to Chittagong Medical College Hospital in critical condition.

Later, the angry tribal people went on the rampage, damaging auto-rickshaws, buses and trucks in the area, disrupting traffic.

On information, army personnel rushed to the spot and brought the situation under control.