Awwal 04, 1432 H / April 08, 2011, SPA -- Stalking the halls of his one-time elementary school, 23-year-old Wellington Oliveira killed 10 girls and two boys, most with shots to their heads even as children begged him to stop, witnesses said, according to AP. Oliveira then took his own life after police gunfire struck his legs and sent him toppling down some stairs, but not before carrying out what crime experts are calling the worst school massacre in Brazil's history. Witnesses said he entered the Tasso da Silveira school in Rio de Janeiro on Thursday armed with two pistols and an ammunition belt, shooting at students and repeatedly yelling: «I'm going to kill you all!» «He had already killed a lot of children in the first floor and in the yard,» student Jade Ramos told the Globo television network. «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 locked the door and barricaded it with tables. Images taken with a cellphone and posted on YouTube showed students fleeing wildly, screaming for help, many with their white and blue school shirts soaked in blood. Families still reeling from the attack were planning for the funerals of their children Friday, while Brazilian President Dilma Rousseff said she would do her best to attend the memorials. «I ask for one minute of silence for these children who were taken so early from their life,» Rousseff said, her eyes welling with tears. «It's not in the nature of our nation to have these types of crimes.» With a dozen children dead, 11 more were in hospitals for wounds or other injuries, at least two of them reported in grave condition. The ages of the children were not immediately known, though the school serves grades one through eight. Elias da Silva paced outside a hospital waiting for news of his nephew, a 14-year-old boy who slipped on a pool of blood and twisted his ankle as he fled the school pulling along a friend during a moment when the gunman stopped to reload. His nephew escaped, but the girl was shot in the back and died, the uncle said. «I asked God for him to come out alive and he did,» Silva said. «He came out running and still thought to try to save his friend. This is going to be difficult for him to understand.» Andreia Machado tearfully recounted what her 13-year-old daughter, Thayane, told her before going into surgery. Thayane was struck by three bullets and lost feeling in her legs because one hit her spine, the mother said. With tears streaking her cheeks, Machado wondered if her daughter would ever be able to 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.» Officials said Oliveira had once attended the Tasso da Silveira school in a working-class neighborhood in western Rio. The motive for the attack wasn't known, but authorities said the shooter 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, which was posted on the Globo television network's website. Edmar Peixoto, the deputy mayor of western Rio, said the letter also stated the gunman had the AIDS virus. Oliveira's neighbors told the newspaper Jornal do Brasil they couldn't believe the quiet young man who kept his head down and stayed out of trouble was responsible for so much bloodshed. «He was never violent; he didn't get in trouble, throw stones, or fight in the streets,» said Edna de Lira Ferreira, 55. «He was just quiet, and we respected the way he was. He just stayed in his room, in front of the computer.» Oliveira had been a Jehovah's Witness, like his adoptive parents and their other five children, Ferreira said. Another neighbor, Elma Pedrosa, remembered Oliveira as an unusual youth who looked away when he passed acquaintances rather than greet them. «He was anti-social, but he never demonstrated any violent tendencies,» she said. The public school was in the midst of celebrating its 40th anniversary, and students' handmade posters commemorating the day could be seen through school windows. About 400 people were inside the school when the shooting began about 8:30 a.m. When Oliveira first entered the school he told staff members he was there to give a lecture, Rio Police Chief Martha Rocha said. Shortly afterward, he opened fire. The gunman had no criminal history, Rocha added at a news conference. Rio is a city rife with drug-gang violence in its vast slums, but school shootings are rare. «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. Police were alerted to the shooting when two young boys, at least one with a gunshot wound, ran up to two officers on patrol about two blocks away. The officers sprinted to the school and at least one quickly located the gunman on the second floor and traded shots with him. «He saw me and aimed a gun at me,» officer Marcio Alves said. «I shot him in the legs, he fell down the stairs and then shot himself in the head.» 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. Authorities closed the school temporarily while they investigate, but Paes said it would reopen. Rio Gov. 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.