A man, 57, shot dead three people in the northeastern province Nong Bua Lamphu on Wednesday morning.
The shooting spree happened in tambon Non Muang at about 6.30am.
CCTV footage showed the gunman, dressed in black, walking towards another man who was sweeping the roadside.
The gunman drew a pistol from his jacket pocket, waited for a tractor to pass him and crossed the road.
The gunman stopped close to the victim and shot him in the head at point-blank range.
After the victim fell to the ground, the gunman fired more shots at him before walking back across the road.
He then ran towards a woman who sat on a bench nearby. Having heard the gunshots, she ran for her life and managed to escape.
The gunman then shot two more people, a man and a woman. According to local media, the suspect was identified as Mr Samart. He fled the scene on a blue motorcycle.
Police are trying to find him.
