Salvador Ramos, 18, then opened fire with an assault rifle he legally bought on his birthday, systematically shooting each one.
During the horror scenes at Robb Elementary School in Uvalde, one heroic 10-year-old girl bravely tried to save her classmates as she called 911 for help.
Amerie Jo Garza was killed before she could be connected to police.
Her grandmother Berlinda Irene Arreola said Ramos told the children, "You're going to die," before opening fire.
The heartbroken grandmother said: "Instead of grabbing it [her phone] and breaking it or taking it from her, he shot her.
"She was sitting right next to her best friend. Her best friend was covered in her blood.
"She died a hero trying to get help for her and her fellow classmates.
Amerie had been photographed at 10am holding up her honour roll certificate. Then, just 90 minutes later, she was dead.
The children, aged between eight and 11, were finishing their last days of school before breaking up for the end of term when Ramos entered their classroom.
Scared
Miraculously, a nine-year-old survived despite being shot in the leg. The unnamed boy's grandmother said the massacre happened in his classroom.
She said: "He's scared right now. He said he was scared, but he's fine. It didn't do any damage, hopefully no nerve damage and stuff, but he was just released and we thank God for that.
"We're praying for all of the children that were taken by this mass murderer."
The slaughter is the worst school shooting in the US since the 2012 Sandy Hook massacre in Connecticut, which left 26 youngsters dead.
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Denne historien er fra May 26, 2022-utgaven av Daily Express.
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