At least 21 people were killed after a boat carrying over 100 passengers capsized in Bangladesh's Titas River following a head-on collision with a sand-laden vessel, which got hit by another ship from behind, authorities said on Saturday.A passenger, Ali Akhter Rizvi, told IANS that the boat left the Champaknagar ghat of Vijaynagar upazila of Brahmanbaria district at around 4.30 p.m. on Friday evening. It was heading to Anandabazar ghat of Sadar upazila.The collision took place in the Laisca Beel area after which the boat overturned and sank, Rizvi added.Hayat Ud Daula Khan, the Deputy Commissioner of Brahmanbaria, confirmed the toll and added that the families of those who died were being paid 20,000 taka each and the injured have been hospitalised.Authorities also said that many were still missing, but did not give an exact figure.Meanwhie, several rescue teams and divers from the fire service are operations to locate the missing persons.