Three labourers were killed and four others suffered injuries when a mango-laden tractor they were travelling plunged into a roadside canal at Kondapavuluru village near Gannavaram road on Wednesday. The deceased have been identified as – Chennu Sunitha (17), Ch. Kumari (30) and Bathula Kasulu (32) – all natives of Bathulavarigudem village in Nuzvid mandal. The vehicle was heading towards Nunna from Gannavaram in Krishna district, said the Gannavaram police.