Three workers involved in road-widening work along the Vaigai North Bank Road were killed when a concrete mixing vehicle ran over them on the riverbed in the small hours of Thursday.
The deceased were identified as Venkatesan (27), Periasamy (34) of Idapatti near Salem and Babu (37) of Chennai.
The police said all the three workers were sleeping on the riverbed, on which a truck path has been laid, for trucks involved in carrying construction materials for the National Highways Authority of India for the widening of the North and South Bank Roads.
The driver of the truck, who was moving the multi-axle vehicle on the riverbed in reverse, failed to notice the workers sleeping and the heavy vehicle ran over them at around 4 a.m.
While Venkatesan and Periasamy were killed on the spot, Babu, who suffered fractures on his legs succumbed to injuries at the Government Rajaji Hospital.
Mathichiyam police are investigating.
Two killed in Virudhunagar district
Two motorists were killed when an unidentified vehicle knocked down a two-wheeler on which they were riding on the Tiruchuli-Parthibanoor Highway near Pallimadam on Thursday morning.
The police identified the victims as Palani (20) and Backiyam (38).