The ultras surrendered yesterday and deposited two SLR, one AK-47 rifle, one Insus riffle, one G-3 rifle, two grenades, 369 live cartridges and some documents, SP (Police Control) Uttam Bhaumik said.
They surrendered before SP (Special Branch) Arindam Nath in presence of BSF officials, he further said.
Bhaumik said twelve tribal youths also returned along with the ultras, who fled from the base camp with arms and ammunition.
The tribal youths were forcibly taken to the NLFT base camp at Sapchhari under Rangamati district in Chittagong Hill Tract (CHT) of neighbouring Bangladesh.