A man has invaded a daycare centre and killed four children with a hatchet in southern Brazil, authorities have said.
Five more wounded children were taken to hospitals, with one in a serious condition, after the attack in the city of Blumenau on Wednesday.
Those killed were between the ages of five and seven, authorities said.
The assailant, who is reported to be a 25-year-old man, turned himself in at a police station and did not appear to have any connection with the centre, which offers nursery services, preschool education and after-school activities.
Amid rumours on social media of other potential attacks, Blumenau's mayor Mário Hildebrandt said the city has suspended classes and will declare a 30-day mourning period.
Santa Catarina state Governor Jorginho Mello confirmed the killings on his Twitter account, and wrote that the killer has been arrested.
Images broadcast on television showed weeping parents outside the private daycare centre, named Cantinho do Bom Pastor.
Valeria Aparecida Camilo, the mother of a five-year-old girl at the centre, said she was at work when a colleague saw the news.
She called her husband, Gustavo, who rushed to the school and later learned that his daughter had survived.
“The moment I saw her, it was a relief,” Gustavo Camilo said outside the centre.
“But we feel sorry for everything that has happened, with the other kids who wound up dying.”
Valeria added: "They’re five years old. What did a five-year-old do to this person?”
Franciele Chequeto said one of the girls killed was friends with her seven-year-old son, Gabriel.
She said: “He wasn’t understanding. I sat down and told him that he no longer will be able to see some of his little friends.”
Local media reported the attacker scaled a wall to enter the daycare centre wielding a hatchet.
Police believe the attack was an isolated act and not related to any other crimes.
Authorities are searching for a motive, Ronnie Esteves, the police detective leading the investigation, told reporters.
Brazil's President Luiz Inácio Lula da Silva wrote on Twitter: “There is no greater pain than that of a family who loses its children or grandchildren, even more so in an act of violence against innocent and defenceless kids.
“My thoughts and prayers are the families of victims and the community of Blumenau in the face of the monstrosity of what occurred.”
School attacks in Brazil had been uncommon, but have begun happening with greater frequency in recent years.
Last week, a student in Sao Paulo stabbed a teacher, killing her, and also wounded several others.
“May God comfort the hearts of all families in this moment of deep pain,” Mr Mello wrote on Twitter.
Blumenau, a city of 366,000 people, is famous for its annual Oktoberfest festival.
Hours after the attack, Brazil's justice and education ministers pledged to invest in new violence-prevention efforts.
Education Minister Camilo Santana announced the creation of a group to address school violence.
Santana will lead the group, which is scheduled to meet for the first time on Thursday.
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