Three trucks were involved in the collision near Goverdhanpura was a collision between three trucks, SHO Kotputli police station Ravindra Pratap said.
A speeding truck rammed into a stationary truck on the highway, while the truck in which the victims were travelling was behind the speeding truck and dashed into it, he said.
Pratap said the truck caught fire after collision and the four trapped inside a cabin of the truck were burnt to death.
The fire was controlled later and the charred bodies were moved to a local hospital, he added.