Connecticut state police say multiple 30-round magazines and hundreds of bullets found at the elementary school where 26 were killed.
State Police Lt. Paul Vance also said Sunday that authorities have officially identified the gunman in the school rampage as Adam Lanza. They say his mother, Nancy, as was one of his victims.
Residents of Newtown are preparing for a visit by President Barack Obama. He is scheduled to attend an interfaith vigil in the evening.
The shooting is the largest massacre of school-age children in U.S. history.
Suspect's mother shot first
Lanza shot his mother, Nancy Lanza, drove to the school in her car with at least three of her guns, and opened fire in two classrooms around 9:30 a.m. Friday, authorities said.
A custodian ran through the halls, warning of a gunman, and someone switched on the intercom, perhaps saving many lives by letting them hear the chaos in the school office, according to a teacher. Teachers locked their doors and ordered children to huddle in a corner, duck under their desks or hide in closets as shots reverberated through the building.
Among those killed was the school's well-liked principal, Dawn Hochsprung. Town officials said she died while lunging at the gunman in an attempt to overtake him. A woman who worked at the school was wounded.
Maryann Jacob, a clerk in the school library, was in there with 18 fourth-graders when they heard a commotion and gunfire outside the room. She had the youngsters crawl into a storage room, and they locked the door and barricaded it with a file cabinet. There happened to be materials for coloring, "so we set them up with paper and crayons."
After what she guessed was about an hour, officers came to the door and knocked, but those inside couldn't be sure it was the police.
"One of them slid his badge under the door, and they called and said, `It's OK, it's the police,'" she said.
The district superintendent said she was told another teacher pushed students in the kiln room until police let them out.