A 12-year-old girl wounded in a school shooting in Thailand has died, raising the death toll to nine, authorities said. The girl died Saturday from critical injuries suffered in the attack at Debsirin Nonthaburi School in Nonthaburi province, northwest of Bangkok. The gunman, a 14-year-old student, opened fire at the school at about 10 a.m. Friday, killing five people. Earlier that morning, he had killed his two grandparents at his family home, officials said. He then apparently took his own life. Twenty-three people were injured in the rampage. The weapon used was his grandfather's firearm, according to officials. The attack was Thailand's most devastating mass killing in nearly four years.