Brazilian media outlets say the 13-year-old suspect appeared to be inspired by a deadly school shooting in 2019.
A teacher has been fatally stabbed in an attack at a school in Sao Paulo, Brazil, that left three other teachers and two students injured.
Officials have identified a 13-year-old student as responsible for the knife attack, which took place at about 7:20am local time (10:20 GMT) on Monday at the Thomazia Montoro public school.
The governor of Sao Paulo state, Tarcisio Gomes de Freitas, said on Twitter that the suspect had been apprehended. No motive has been confirmed so far.
“I have no words to express my sadness,” de Freitas wrote in his post.
He also expressed “much regret and sadness” at the death of 71-year-old science teacher Elisabete Tenreiro, who was killed in the attack. After being stabbed, officials say Tenreiro went into cardiac arrest and died.
Three days of mourning have been announced in remembrance of Tenreiro. Officials said the injured teachers and students were being treated at four local hospitals.
Sao Paulo’s Secretary of Public Safety Guilherme Derrite applauded the “heroic acts” of a physical education teacher who “immobilised” the teenage suspect, thereby avoiding “a greater tragedy”.
In an interview with the Associated Press news agency, a 13-year-old from the school said the suspect, a classmate, had been in a fight with another student the previous week and that Tenreiro had intervened.
He added that the suspect appeared angry at Tenreiro and threatened to do something about the teacher’s actions.
On Monday morning, the student said the suspect appeared dressed in a skull mask and stabbed the teacher from behind.
Brazil’s Folha newspaper reported that the suspect wrote under the username “Taucci” on Twitter, a seeming reference to a March 2019 school shooting that took place in Suzano, on the outskirts of Sao Paulo.
There, two former students, identified as 17-year-old Guilherme Taucci Monteiro and 25-year-old Luiz Henrique de Castro, opened fire at the Raul Brasil State School, killing five students and two school employees before they died by suicide. Ten other students also were injured.
Investigators later said that Monteiro and Castro were inspired by the 1999 Columbine High School massacre in the United States, which was, at the time, the deadliest school shooting in that country’s history.
It has since been surpassed by shootings at Sandy Hook Elementary School in 2012, Marjory Stoneman Douglas High School in 2018, and Robb Elementary School in 2022.
Another US school shooting took place in Nashville, Tennessee, on Monday morning, the same day as the attack in Brazil. Six people, including three children, were killed in that attack.
The incident in Brazil on Monday also comes nearly a month after a teacher in southwest France was stabbed to death by a 16-year-old student.
Brazilian officials said that the 13-year-old suspect in Sao Paulo had researched firearm purchases online before the stabbing attack.
Al Jazeera and news agencies