Nell Malyszka and Trish Keil teach music to children in Sandy Hook, Connecticut, where gunman Adam Lanzo massacred 20 youngsters and six adults.
The twins, who moved to the US from Edinburgh in 1975 with their brother Matt Wilkie, say they know many of the murdered children.
The sisters say they are struggling to come to terms with the deaths and are trying to make sense of the horror.
Mrs Malyszka said: "We'll always remember December 14. It's like 9/11 for this small town. But we will overcome because good does overcome evil. There's more good – there has to be."
Ms Keil said the massacre needed to be a wake-up call for their adopted homeland.
She said: "Something has to come out of this. Some good has to come out this – there has to be a change."
Mrs Malyszka is a co-director of the Suzuki Talent Education School of Sandy Hook, where the sisters teach music and give lessons in piano and classical guitar.
Mr Wilkie is a contractor in nearby Southbury.
The Scots siblings are talented musicians and well-known faces in the Newtown area, where they perform in a band called Eclipse.
Mrs Malyszka's husband Ron said the events had shattered his wife, her siblings and their family in Scotland, who have visited the area.
He said: "They teach pre-school children so only know them by their first names but Nell recognised some of the names on the list of those who were killed. It's horrific and has strengthened our family's belief that America must get rid of guns."
The Scots trio are from the Muirhouse area of the capital and have made several trips home since emigrating.
They have all lived in Newtown at various times and Mrs Malyszka's music school is only half a mile from the scene of the massacre.