UPDATE: The death toll reportedly grew to 20.
Sergeant Major Jakapanth Thomma stole an army vehicle and killed several people in a shooting rampage in the northeastern city of Nakhon Ratchasima.
There are conflicting reports on the casualties in the attack. Local media said at least 12 people were killed. The AFP news agency quoted health authorities as saying that the death toll stood at 17.
The gunman has not been neutralized yet.
The situation is developing.