The victims included 24 children and 12 adults, according to a report posted on the Facebook page of the provincial public relations department. Another 12 people were reportedly injured.

The shooting occurred at around 12:40 p.m. local time. The attacker, a 34-year-old former police officer, later killed his family members before taking his own life, said Kornwit Nitkhamhan, deputy inspector at Na Klang Police Station.

"About the horrifying incident, I would like to extend my deepest condolences to the families of the dead and injured," Thai Prime Minister Prayut Chan-o-cha wrote on his Facebook account, adding that he has ordered the national police chief to "fast-track an investigation."

TV footage showed ambulances and families of the victims gathering outside the childcare center. A woman working at the childcare center told a local TV program that they were having lunch when she heard the sound and saw the injured falling to the ground.

The shooter broke the window in as the door was locked. This childcare worker, however, succeeded in fleeing the scene.

Many locals rushed to the Nong Bua Lamphu provincial hospital in response to its urgent call for blood donation for the injured.