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

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

He then left that school — a public primary and secondary school — and went to a nearby private school, where he killed an adolescent girl and wounded two other people, officials said.

Authorities have arrested the shooter, said Governor Renato Casagrande, who declared three days of mourning in the state.

“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 he was undergoing psychiatric treatment,” Casagrande told a news conference.