The perpetrator was a 14-year-old student who took his own life after the attack, according to Thai police.
The prime minister promises to further restrict the ability to carry firearms in public places. Only on-duty government personnel will be allowed to carry weapons.
The gun used in the attack belonged to the 14-year-old's grandfather and was legally registered, according to police. Thailand has about 10.3 million firearms in civilian possession, of which about four million are believed to be illegal.
The country has relatively strict gun laws, with ten years in prison for illegal possession, but enforcement is a problem.
As minister of home affairs, Charnvirakul pushed through a temporary moratorium on new gun licenses.
