DERA GHAZI KHAN, April 1: Three devotees were killed and as many others injured when a tractor-trolley overturned at Mangu Gatta near Sakhi Sarwar Sharif, some 35km from here, on Friday. Those killed are Asghar, Shamim Mai and Naseem Bibi, and the injured Aasif, Aslam and Ghulam Meerwan. The injured were taken to the DHQ Hospital.