On Friday night, hundreds of people packed a Newtown church and stood outside in a vigil for the victims. People held hands, lit candles and sang "Silent Night" at St. Rose of Lima church.
Mergim Bajraliu, 17, said he heard the gunshots echo from his home and ran to check on his 9-year-old sister at the school. He said his sister, who was uninjured, heard a scream come over the intercom. He said teachers were shaking and crying as they came out of the building.
"Everyone was just traumatized," he said.
Mary Pendergast said her 9-year-old nephew was in the school at the time of the shooting but wasn't hurt after his music teacher helped him take cover in a closet.
Richard Wilford's 7-year-old son, Richie, told him that he heard a noise that sounded like "cans falling." The boy said a teacher went out to check on the noise, came back in, locked the door and had the children huddle in the corner until police arrived.
"There's no words," Wilford said. "It's sheer terror, a sense of imminent danger, to get to your child and be there to protect him."
On Friday afternoon, family members were led away from a firehouse that was being used as a staging area, some of them weeping. One man, wearing a T-shirt without a jacket, put his arms around a woman as they walked down the middle of the street, oblivious to everything around them. Another woman with tears rolling down her face walked by, carrying a car seat with a baby inside.
"Evil visited this community today and it's too early to speak of recovery, but each parent, each sibling, each member of the family has to understand that Connecticut - we're all in this together. We'll do whatever we can to overcome this event," Gov. Dannel Malloy said.
Adam Lanza and his mother lived in a well-to-do part of Newtown where neighbors are doctors or hold white-collar positions at companies such as General Electric, Pepsi and IBM.
At least 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, authorities said.
The shootings instantly brought to mind such tragedies as the Columbine High School massacre that killed 15 in 1999 and the July shootings at a movie theater in Aurora, Colo., that left 12 dead.
"You go to a movie theater in Aurora and all of a sudden your life is taken," Columbine Principal Frank DeAngelis said. "You're at a shopping mall in Portland, Ore., and your life is taken. This morning, when parents kissed their kids goodbye knowing that they are going to be home to celebrate the holiday season coming up, you don't expect this to happen."
He added: "It has to stop, these senseless deaths."
Obama's comments on the tragedy amounted to one of the most outwardly emotional moments of his presidency.
"The majority of those who died were children - beautiful little kids between the ages of 5 and 10 years old," Obama said.
He paused for several seconds to keep his composure as he teared up and wiped an eye. Nearby, two aides cried and held hands as they listened to Obama.
"They had their entire lives ahead of them - birthdays, graduations, wedding, kids of their own," Obama continued about the victims. "Among the fallen were also teachers, men and women who devoted their lives to helping our children."
Associated Press writers Jim Fitzgerald and Pat Eaton-Robb in Newtown, Bridget Murphy in Boston, Samantha Henry in Newark, N.J., Pete Yost in Washington and Michael Melia in Hartford contributed to this report, as did the AP News Research Center.
Copyright 2012 The Associated Press.