Police says that he kill himself and his family after one manhunt following the attack in Nong Bua Lamphu province.
Children and adults was among the casualties for the nursery – police says the attacker shoot and stab the victims before he escaped.
The motive was not clear. Police says that they dismiss the officer last year.
The victims of the attack was reported to include children as young as two. At least 12 people also wound.
“The shooter comes during lunch time and shoot four or five officials for the childcare centre first,” one local official Jidapa Boonsom, that worked nearby, tell Reuters news agency.
“The first people thought that it was fireworks,” she said, the gunmen that enter force break the locks room where children slept.
Thailand Prime Minister Prayuth Chan-ocha describe the shooter as “a shocking event”.
Police called the attacker Panya Kamrab. He was escape from the comot di scene inside a white-four door Toyota pick-up truck with Bangkok registration plates.
One senior police officer in Nong Bua Lamphu province says that 23 children was among the casualties, AFP news agency report.
He says that Kamrab, the police lieutenant colonel, was the person that dismiss last year drugs use.
Mass shootings in Thailand although gun ownership rates was somehow high in the region. Illegal weapons is also common in the south-east Asian country, according to Reuters news agency.
The nursery attack comes less than a month after one army officer shoot two of his colleagues in Bangkok.
In 2020, one soldier kill 29 people and injure more people in the city of Nakhon Ratchasima.