The mishap occurred this afternoon near Gunsari village under Takhatpur police station limits when the victims were going on the motorcycle towards Takhatpur from Bilaspur, a local police official said.
"As per the information, the motorcycle, on which the four victim were travelling, collided with the dumper at a curve near Gunsari, leaving three of them dead on the spot and another one injured," he said.
Those killed were identified as Vinod Kaushal (26), Karan Jhonsan (16), Gugla Miri (3), while Amar Satnami sustained serious injuries, he said.
After the mishap, the truck driver fled from the spot but his vehicle was impounded and a case has been registered in this connection, he said.