At least seven people have been killed and 23 injured after a 14-year-old boy opened fire at his home and school on the outskirts of Thailand's capital, Bangkok. The gunman - a student at the Debsirin School in Nonthaburi - killed his grandparents and five teachers before taking his own life, Thai Prime Minister Anutin Charnvirakul told reporters. The attacker still had "more than 30 bullets left" when he turned the gun on himself, Anutin added. The shooting - the second at a school in Thailand this year - has renewed pressure on the government for greater action on gun control. Police were deployed to the scene during the active shooting, which began just after 10:00 local time (03:00 GMT). National police chief police Gen Kittiratt Phanphet told reporters that forensic officers had found the gunman's shots were quite accurate, with several hitting vital spots on the body. The prime minister said the attack was "well prepared" with "clear steps and clear goals". A female seventh grader, still in school uniform, told the BBC she was standing in front of her teacher when the woman was shot. Still in her uniform, with her mother by her side, she explained how the shooter stalked from room to room.