Witnesses reported that 100 rounds may have been fired.
Police arrived to find “a tragic, horrific scene” of murdered children in their classrooms, Connecticut State Police Lieutenant Paul Vance said in a briefing for reporters.
Eighteen children were found dead in the school. Two who had been wounded died later in hospitals. Only one person wounded in the attack survived, police said.
Heavily armed officers spent hours searching cars and homes, even the school roof, looking for evidence or for additional gunmen. The AP reported that police recovered three guns from the school grounds, including a rifle found in a car.
Teachers and school staff evacuated students, many without their coats, to a nearby firehouse. Authorities contacted parents through an electronic notification system, and then began the excruciating task of accounting for each of nearly 700 children who attend the school, including those who might have been home sick.
Joe Wasik, 42, a Newtown resident, said his wife called him at work around 10 a.m., saying she had received an alert about an emergency at the school where their daughter, Alexis, is a student.
Wasik sped to the firehouse. “I just wanted my daughter.”
Inside the firehouse, children were grouped by age. “There were so many people, everyone was looking for their kids,” he said. “It was pandemonium.”
His daughter cried when he hugged her. She told Wasik that a teacher had hidden her class in a closet.
Some of the parents who had lost children stayed well after dark at the firehouse, police said. The Rev. Robert Weiss, pastor of St. Rose of Lima Church, spent the day with the families, including members of his church, who would come to worship with “beautiful little children. . . . I’ve watched them grow.”
He struggled to describe the scene: “There’s no words. There’s been a lot of hugging and crying and sharing memories. Many parents came in with pictures of their children. The feeling will be there for a long time.”
The tragedy dwarfed the nation’s political problems, at least for the moment. House Speaker John A. Boehner, who has been battling the president over taxes and spending, canceled the traditional weekly GOP radio address, “so that President Obama can speak for the entire nation at this time of mourning,” Boehner said in a statement.
In Newtown on Friday evening, families gathered for a vigil at St. Rose of Lima.
“My grandson is 6, so this hits home,” said George Reichert, 64, attending with his wife, Michelle. “We don’t know anyone personally, but we do know them: they’re our neighbors. We see them around town, at the supermarket, at the coffee shops.”
Rob Cox said he grew up in Newtown. His family lived in Europe but moved back to Newtown because he wanted a safe community with great schools.
“There are no big losses in our immediate circle, thank God,” Cox said. “But these are all our kids. These are Newtown’s kids. We claim them.”
Globe correspondents Zachary T. Sampson, Matt Rocheleau, Jaclyn Reiss, Derek J. Anderson, and Melanie Dostis contributed to this report, Rocheleau and Reiss from Connecticut and Sampson from New Hampshire. The article was written by Mark Arsenault in Boston. He can be reached at email@example.com.