Three children were stabbed to death by a classmate at a Brazilian school on Tuesday, in the second consecutive attack in just 24 hours, days after a 25-year-old man broke into a daycare center and killed four toddlers with an ax.

Yesterday’s attack took place at a public school in Santa Teresa, a small town in the central state of Goia. The perpetrator was a 13-year-old boy who, after throwing a firecracker in a classroom, attacked his classmates with a knife as they were leaving the classroom.

The three injured children are being treated out of danger, police said, without specifying their ages.

The attacker then chased a teacher, who locked herself in a school room to escape. The 13-year-old was immobilized by a teacher until the police arrived.

In a search of his home, officers found “notes and material indicating that he had been planning this attack for some time,” authorities said.

On Monday, a teenager stabbed two students and a teacher at a private school in Manaus (north). Local media reported “superficial injuries”. The perpetrator surrendered and is being interrogated by the police.

Last Wednesday, a 25-year-old man broke into a kindergarten in the city of Blumenau in the state of Santa Catarina (south) and killed four children aged 4-7 with an ax.

The massacre shocked all of Brazil and sent “panic to schools and parents of students,” Justice and Public Security Minister Flavio Dino said late Monday, calling for tighter controls on content circulating on social media platforms.

Several messages on social networking platforms contain threats to attack schools, the French News Agency (AFP) points out.

A video shared by several users advises parents not to send their children to school on April 20, the 24th anniversary of the Columbine High School massacre in the US.