The tragic accident happened on Kilometre markers 168-169 on the highway.
Highway police said the interprovincial bus driver fled the scene after the fatal accident which badly tore apart the left front body of the bus.
Those who died and were injured were seated on the left side of the bus, police said.
All were admitted to Non Soong hospital in Non Soong district and Maharaj hospital in Korat.
The police said the 18-wheel trailer with asphalt loads was at the rear of a number of trucks waiting for weight checks at the station when the bus rammed at its rear.