Lyn's Lakorns has the story:
The accident occurred at a farm in Phanom Phrai. It started to rain so the owners of the farm took shelter under their livestock stable; the Yam Yasothon 2 filming crew members ran for cover to a shack 50 meters away. There was loud thunder, which scared everyone, and then the frantic cries of a child was heard. Everyone followed the sound of a child crying and found three dead bodies ... Phaibun Songchalee, 75, the owner of the farm, his wife Patma Songchalee, 61 and their daughter Wanlapa Songchalee. 27. Miraculously, Wanlapa’s 2-year-old daughter Apinyapon Inthawong survived.
None of the cast or crew were injured. Mum heard of the deaths when he was at his hotel in Yasothon. He was to have met the Songchalees that very day to thank them for for the use of their farm, which they had agreed to let the film company use for free. Mum said he was would pay for and take part in funeral services for the family.