Wellington Menezes de Oliveira also shot and wounded 12 others -- many in the head -- and only stopped firing when he was shot in the leg by a police officer and turned one of his revolvers on himself, officials said.

A rambling, religiously-themed suicide note was found in his clothes but it shed little light on the motivation of his macabre attack on defenseless young children, aged between nine and 15, as they arrived for morning class.

President Dilma Rousseff, who only took office in January, could not hold back the tears as she shared her grief with a nation struggling to comprehend what was the worst school shooting in Brazil's history.

Police cordoned off the three-story building in Rio's Realengo district as they interviewed residents and parents to find out what happened, while a local hospital called for people to give blood.

"Employees of the school told officers the young man arrived well-dressed and carrying a backpack and said he told them he had been invited to speak with students for a conference," explained fire spokesman Evandro Bezerra.

AFP