Wilaiwan Iankanna, 41, was killed behind the wheel.
The injured were identified as Kasamon Iakanna, 12, Thamolwan Iankanna, three, Napat Iankanna, 11, Chakkarin Iankanna, 43, and Thongbai Iankanna, 80.
The survivors told police that they were returning home to Chon Buri from Surin when the vehicle suddenly hit the tree.
Police suspect the driver fell asleep.