
All the victims were anti-government protesters returning from a Bangkok rally, judging from symbolic Thai national flag straps tied to whistles on their necks.
Police said the driver, who died on the way to a hospital, was probably tired and fell asleep at the wheel, before the vehicle veered off a road and hit the pillar.
Two occupants died instantly at the scene, and those injured have been hospitalised.
The vehicle carried a Surat Thani licence plate, and was |heading home through Chumphon.