Police said the accident happened after midnight on Thursday on Phetkasem Road in Tambon Thong Mongkol, Bang Saphan district. 
The van was taking 12 Myanmar workers from Koh Pha Ngan in Surat Thani province to Mae Sot district in Tak, as the workers were having holidays for Songkran. 
The injured driver was identified as Weerachai Laktitham, 39. The three injured Myanmar workers were identified as Thun Khant Zin, 22, Thidar Win, 32, and Ken Thanthe, 52. 
The injured were rushed to Bang Saphan Hospital. 
Police suspect the driver may have dozed off, causing his van to veer off and roll into a dry ditch in the middle of the road before banging into the tree.

Driver, three Myanmar workers injured in road crash

A Thai driver and three migrant women workers were injured when a van taking 12 Myanmar workers home for the Songkran holidays rammed into a tree in the middle of a road in Prachuap Khiri Khan province.