Wellington de Oliveira, 24, killed 13 children and injured 20 more in yesterday's attack on Tasso de Oliveira elementary school in the Realengo suburb of Rio de Janeiro.
In one CCTV image, the former pupil can be seen holding his gun outside the classroom where he launched his bloody spree before turning the weapon on himself.
The gunman roamed the halls of the school for children aged 10 to 15, lining his victims against a wall and shooting them in the head at point blank range as he shouted 'I'm going to kill you all!'
Killing spree: 24-year-old Wellington de Oliveira shot dead 13 children at a Rio de Janeiro school and then himself
The pupils can be seen fleeing from the carnage. Eleven of their classmates were killed before the gunman turned the weapon on himself.Pupils are seen on security cameras running from the classroom in Tasso da Silveira school after the gunman opened fire.The pupils can be seen fleeing from the carnage. Eleven of their classmates were killed before the gunman turned the weapon on himself.One of the pupils exits the classroom with a bullet wound in his shoulder after the attack in the Realengo neighborhood of Rio.The security camera image shows Wellington Menezes de Oliveira, 24, walking inside a corridor of the Tasso da Silveira school with a gun in his hand
He had told school officials who approached him that he was there to deliver a speech, and then opened fire on students with two pistols.
Two boys, one with a gunshot wound, fled the school ran to two police officers on patrol two blocks away.
The officers sprinted to the school and exchanged fire with the gunman.He was hit in the leg, fell down and realising he was caught, shot himself in the head.
'He saw me and aimed a gun at me,' said officer Marcio Alves. 'I shot him in the legs, he fell down the stairs and then shot himself in the head.'
Jade Ramos, a student at the school, said the gunman repeatedly yelled 'I'm going to kill you all!'
'He had already killed a lot of children in the first floor and in the yard,' she said.
'He kept telling the kids to face the wall and was shooting at their heads. The children kept begging, 'No, please!' There was a lot of blood, children agonizing on the stairs.'
Ramos said she escaped by running into a classroom, where a teacher then locked the door and barricaded it with tables.
'He came in shooting,' said Andreia Machado, recounting what her 13-year-old daughter, Thayane, told her before going into surgery.
Thayane was hit by three bullets and lost feeling in her legs because one hit her spine, said her mother. Crying as she spoke, Machado wondered if her daughter would ever be able to return to school - or walk.
'She's such an active child,' she said. 'That's the biggest fear I have, her not being able to walk again. But we have to trust in God.'
Those killed were between the ages of 12 and 15. One of the boys died at a hospital about 12 hours after the shooting.
Oliveira left a rambling and mostly incoherent letter at the scene indicating he wanted to kill himself.
The letter also explained in detail how Oliveira wanted his corpse to be cared for - bathed and wrapped in a white sheet that he left in a bag in the first room where he said he would start shooting. The letter also states that the gunman should not be touched by anyone who is 'impure' unless they wear gloves.
'If possible I want to be buried next to my mother. A follower of God must visit my grave at least once. He must pray before my grave and ask God to forgive me for what I have done,' read the letter, portions of which were posted on the Globo television network's website.
Edmar Peixoto, the deputy mayor of western Rio, said the letter also stated the gunman had AIDS.
About 400 people were inside the school when the shooting began about 8:30 a.m. local time.
'What happened in Rio is without a doubt the worst incident of its kind to have taken place in Brazil,' said Guaracy Mingardi, a crime and public safety expert at the University of Sao Paulo.
Rio Mayor Eduardo Paes said life at the four-story, pastel yellow and green school was turned into a 'hellish nightmare'.
'This day would have been so much worse if it weren't for the hero policeman,' Paes told reporters at the school.
Rio Governor Sergio Cabral called the shooter a 'psychopath' and said there were no indications anyone else was involved in the shooting, but that the investigation would continue.
'We have to investigate where he got the weapons and where he learned to use them,' the governor said.
Terrified parents rushed to the school in the Realengo neighborhood. Television images showed them crying and screaming for information about their children.
Zilda Nunes, 67, lives across the street from the school and said three of her grandchildren were inside when the shooting began.
She screamed for help when she heard the gunfire, but didn't enter the building. As students fled, she offered them sugar water to help calm them down, she said.
'There were so many children shot, so much blood,' Nunes said. 'People were asking for help, but what could I do?'
Three helicopters were landing and taking off from a football field next to the school, ferrying the wounded to hospitals.
Brazilian President Dilma Rousseff, attending an event in the capital, Brasilia, lamented the deaths of "defenseless children."
'I ask for one minute of silence for these children who were taken so early from their life,' she said, her voice cracking and eyes welling with tears. 'It's not in the nature of our nation to have these types of crimes.'
Carnage: Firefighters carry the body of the suspect from the building after he opened fire with a handgun
Distraught: Parents scream for information after the shooting this morning
Motive? The gunman, believed to be a former pupil at the school, left a note stating he wanted to kill himself
Worst nightmare: Anxious parents and relatives of pupils wait outside school desperate for news of their loved-ones
Ready for action: Armed police arrive at the school after the alarm was raised
