Sichon superintendent Pol Colonel Chokdee Rakwattanaphong said police investigators found that the 40-year-old man, who worked on fishing and tourism boats for living, reportedly argued with his wife often over debts and expenses.
Three days prior to the murder-suicide, his wife reportedly left him with the three children aged 14, eight and four, police said, adding that the house showed no signs of a fight.
Police collected evidence for further investigation and the bodies will undergo autopsies at a morgue in Surat Thani.