NEWTOWN, Conn. —
A law enforcement official identified the gunman as 20-year-old Adam Lanza, the son of a teacher. A second law enforcement official said his mother, Nancy Lanza, was presumed dead.
Adam Lanza's older brother, 24-year-old Ryan, of Hoboken, N.J., was being questioned.
The law enforcement official who said Adam Lanza had a possible personality disorder said Ryan Lanza had been extremely cooperative, was not believed to have any involvement in the rampage and was not under arrest or in custody, but investigators were still searching his computers and phone records. Ryan Lanza told law enforcement he had not been in touch with his brother since about 2010.
All three law enforcement officials spoke on the condition of anonymity because they were not authorized to speak on the record about the unfolding investigation.
The gunman drove to the school in his mother's car, the second official said. Three guns were found — a Glock and a Sig Sauer, both pistols, inside the school, and a .223-caliber rifle in the back of a car.
State police Lt. Paul Vance said 28 people in all were killed, including the gunman, and one person was injured.
Robert Licata said his 6-year-old son was in class when the gunman burst in and shot the teacher.
"That's when my son grabbed a bunch of his friends and ran out the door," he said. "He was very brave. He waited for his friends."
He said the shooter didn't utter a word.
Stephen Delgiadice said his 8-year-old daughter was in the school and heard two big bangs. Teachers told her to get in a corner, he said.
"It's alarming, especially in Newtown, Connecticut, which we always thought was the safest place in America," he said. His daughter was fine.