At least three people, including a teenage girl, were killed and 11 others injured on Friday when a 16-year-old gunman opened fire on two schools in southeastern Brazil, officials said.

Authorities in the city of Aracruz, Espirito Santo state, said the gunman opened fire on a group of teachers at his former school on Friday morning, killing two people and wounding nine others.

He then left that school — a public elementary and high school — and went to a nearby private school, where he killed an adolescent girl and left two others wounded, officials said.

Authorities arrested the shooter, said Governor Renato Casagrande, who had declared a three-day national mourning.

“He was a student at the (first) school until June, a 16-year-old minor. His family then transferred him to another school. We have information that he was under psychiatric treatment,” Casagrande said at a news conference.

He said the lives of some of the survivors were in danger because of their wounds.

“We root and pray for them to recover,” he said.

Surveillance camera footage broadcast in Brazilian media showed the gunman running to the school, dressed in military-style camouflage and brandishing a gun. He then sprinted through the corridors, sending staff fleeing in terror as he began firing shots.

Investigators said he had a swastika on his uniform.

Officials said the shooter, the son of a police officer, used two handguns in the attack, both registered to his father – one his service gun, the other a privately registered gun.

Casagrande said the boy appeared to have carefully planned the attack, breaking in through a locked door and bypassing the school’s security guard.

He then entered the staff room — the first room he came into — and opened fire, the governor said.

“He wanted to shoot people. He opened fire on the first people he met,” he said.

Investigators could be seen carrying the victims’ bodies in coffins and loading them into police trucks in front of the school, which was taped off from the scene, an AFP photographer said.

The city has around 100,000 inhabitants.

School shootings are relatively rare in Brazil but have increased in recent years.

In 2011, 12 children died in Brazil’s deadliest school shooting when a man opened fire and then killed himself at his former elementary school in Realengo, a suburb of Rio de Janeiro.

In 2019, two former students shot and killed eight people at a high school in Suzano, outside Sao Paulo.

Brazilian President-elect Luiz Inácio Lula da Silva called the recent shootings an “absurd tragedy”.

“I was saddened to learn of the attacks,” he wrote on Twitter.

“All my solidarity with the families of the victims… and my support to Governor Casagrande for the investigation and the support of the two school communities.”

Lula, who previously served as Brazil’s president from 2003 to 2010, will take office on January 1 after defeating far-right President Jair Bolsonaro in last month’s elections.

He has sharply criticized Bolsonaro’s dramatic containment of gun laws.

Since ex-army captain Bolsonaro became president in 2019, the number of registered gun owners in Brazil has more than quintupled from 117,000 to 673,000, boosted by a series of presidential decrees relaxing firearms and ammunition regulations.

Public security expert Bruno Langeani of the Sou da Paz Research Institute told AFP the outgoing government’s policies made such attacks more likely.

“The increase in firearms availability in recent years, encouraged by the Bolsonaro government, facilitates this type of episode,” he said.