Witnesses said the clash between Chakoria-Hathazari group and North Bengal group took place when a suspended teacher of the madrasa, Sheikh Ahmed, arrived at the religious institution in the morning.

The madrasa authorities suspended Sheikh Ahmed, who leads the Chakaria-Hathazari group, a week ago on charge of molestation of students.

The North Bengal group, led by Hafez Shamsul Islam and Mohammad Anas, son of the madrasa principal, brought out a procession protesting Ahmed's presence at the madrasa, prompting their rival group to take out another procession.

The two groups then got into a series of clashes, leaving the 30 students injured.

They also set fire to five rooms, including the chamber of Sheikh Ahmed, at 1:00pm. Firefighters rushed to the spot and put out the flame.

Both the groups used machetes and sticks during their 4-hour clash. Three of the injured were admitted to a local health complex with serious injuries.

Additional police force have been deployed in and around the madrasah to fend off any further trouble.