Mergim Bajraliu, 17, 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 fine, heard a scream come over the intercom at one point. He said teachers were shaking and crying as they came out of the building.
"Everyone was just traumatized," he said.
Richard Wilford's 7-year-old son, Richie, is in the second grade at the school. His son told him that he heard a noise that "sounded like what he described as cans falling."
The boy told him a teacher went out to check on the noise, came back in, locked the door and had the kids huddle up 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."
At the White House, a tearful President Barack Obama said he grieved about the massacre as a father first, declaring "our hearts are broken today." He promised action to prevent such tragedies again but did not say what that would be.
The scene in the White House briefing room was one of the most outwardly emotional moments of Obama's 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."