The accident happened today, around midday behind Sir Hubert Murray Stadium at Konedobu in Port Moresby.
According to eye witnesses, the dump truck belonging to POM Stones was fully loaded with sand and was travelling downhill from Lawes Road.
The driver sensing mechanical faults started sounding the horn as a warning, alerting the drivers of other vehicles in front of him to give way.
Before crashing into the vehicle which the victims were in, the dump truck, hit two cars- a taxi and another car. Luckily, passengers of the two cars escaped unharmed.
Eye witnesses say after hitting the two cars, the driver of the dump truck took a left turn.
The pace at which it was travelling together with the weight of the sand, caused the truck to overturn, crushing the red single cab Hilux that had stopped at the roundabout to give way to vehicles coming from Lawes Road.
Police at the accident scene confirmed the elderly driver, and the young boy estimated to be around 10 years old died instantly while one is injured and the other escaped unharmed.
The victims are from Kirakira village.
The driver of the dump truck fled after causing the accident.