The four persons, travelling in motorbikes, were hit by a bus, travelling from Guwahati to Lakhimpur at Patgaon of the district killing three persons on the spot and critically injuring another.
The bus drove away from the mishap site and no arrests have been made so far.
The dead have been identified as Dhrubajyoti Saikia, Niraj Mishra and Gopal Mandal while the injured, Ananta Saikia, has been shifted to Guwahati Medical College Hospital, sources added.