Three people were killed and two others injured in a head-on collision between a truck and ambulance in Adhuria area on the Dhaka-Sylhet Highway under Rupganj upazila of the district this morning.The deceased were identified as Sayed Mullah, 70, his son Nayon Mullah, 37,and ambulance helper Raja Hossain, 18. All of them are inhabitants of Brahmanbaria district.Sub inspector of Kanchpur Highway Police Khairul Islam said the accident occurred when a sand-laden truck collided head-on with an ambulance in the area at about 8.30am, leaving three dead on the spot and two others injured.The injured were sent to Dhaka Medical College Hospital (DMCH) in critical condition.