The accident occurred near Pejerreyes, some 400km north of Santiago near the route of Monday's planned ninth stage between La Serena and Copiapo.
The support truck, carrying tires for rally contestants, was operated by an Argentinean company. It was travelling with a Dakar Rally organization logistical support car.
According to the initial police reports, Argentinean truck driver Marcelo Sanchez crossed the center line for an unknown reason and hit the smaller oncoming vehicle. The two occupants of the vehicle, who were Peruvian, were killed.
Sanchez was jailed pending an investigation, police said.
The famed race is being held in South America because of terrorist fears in Africa, and has already been marred by the death of French motorcyclist Pascal Terry.
Friday's stage brought the race from Argentina into Chile for the first time. Fox Sports