Footage showed the armed robber, wearing shorts and a T-shirt, come out of nowhere and run up to mums with young children by their side with his gun in his right hand before appearing to try to snatch a bag from one of the parents.
The incident happened on Saturday morning with Moreira later dying in hospital from his injuries.
Sao Paulo Governor Mario Franca later honored Sastre for her bravery.
Da Silva, a corporal in the military police, received praise for her actions at a ceremony in her honor on Sunday.More news: Vodafone CEO Vittorio Colao steps down, Nick Read is the new CEO
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Pulling out her own weapon, Ms Sastre is shown shooting the offender three times. According to public security specialists, the decoration of Officer Sastre may send a misleading message to both the police force and to society. She said: "I had to act quickly to end his aggression and prevent him from harming anyone". "I reverted to the training".
The man was actually able to get off a shot that bounced harmlessly off the ground before he crumpled into a heap. On his second attempt at firing, the weapon locked.
He drops his gun, allowing the mother to pin him down until more police officers arrived. A police spokesman said: 'These criminals lose control easily.
The crowd was mostly made up of children and mothers, who have gathered in front of the private school the Jardim dos Ipês suburb of the city to celebrate Mother's Day. "I just thought about defending mothers, children, my own life and my own daughter", Da Silva told Brazilian newspaper O Globo.