On March 13 1996, a lone gunman entered Dunblane primary school when he shot 16 young children and their children.
All the children were between the ages of 5 and 6, and their teacher, Gwen Mayor. 15 other children and teachers were injured during the horrific attack.
Gunman Thomas Hamilton then turned the gun on himself.
The incident shocked the country and sparked a change in the law, making controls on handguns much tighter and with many calling for an outright ban on private handgun ownership.
Many of the survivors of the shootings are now in their 20s.
Andy Murray, who remembers hiding from the gunman during Hamilton’s attack, rarely speaks about his experiences, instead focusing on bringing more positivity back to the quiet, Scottish commuter town.
Murray’s mum Judy later spoke about every parent’s worst nightmare.
She told Radio Times: "Andy's class had been on their way to the gym.
“That's how close he was to what happened. They heard the noise and someone went ahead to investigate. They came back and told all the kids to go to the headmaster's study and the deputy head's study.
"They were told to sit down below the windows, and they were singing songs. The teachers and dinner ladies did an amazing job, containing all these children, feeding them, and getting them out without them being aware of what had happened. I don't know how they managed it."