Anne Marie Murphy, 52, was shielding students inside Sandy Hook Elementary School in Newtown on Friday when she was killed.
Her father, High McGowan, of Katonah, New York, told Newsday that first responders said her body was found in a classroom.
The shooter, who authorities have identified as Adam Lanza, 20, shot and killed 20 elementary students and six adults inside the school. He was found dead inside the building and one of his family members was found dead inside a house in Newtown.
Murphy, who was one of seven children, was a special education teacher at the school, according to Newsday.
"A first responder said she was a hero," High McGowan told Newsday.