The father of the gunman in the Connecticut school rampage says his family is struggling to make sense of what happened.
Peter Lanza said in a statement that "our family is grieving along with all those who have been affected by this enormous tragedy".
Investigators are trying to learn more about Mr Lanza's son, 20-year-old gunman Adam Lanza, who gunned down 26 people including 20 children at a Newtown elementary school after first killing his mother at their home.
They have questioned his older brother who is not believed to have been involved in the rampage.
Mr Lanza said: "No words can truly express how heartbroken we are," and that relatives are "in a state of disbelief and trying to find whatever answers we can".
Nancy Lanza's brother, James Champion, a retired police captain in Kingston, New Hampshire, and other relatives also expressed their "heartfelt sorrow", adding: "The whole family is traumatised by this event."
Mr Downing said the family is trying to understand "the tremendous loss" of those in Newtown.