Newtown, Connecticut (CNN) -- Every time the door bell rings at Aidan Licata's home, the 6-year-old fears the gunman has returned.
He worries the man in black fatigues and military-style vest who opened fire Friday on his Sandy Hook Elementary School classroom -- hitting his teacher and his fellow students -- has found him.
"He still hasn't internalized the fact this gunman, this bad guy, is gone," the boy's mother, Diane Licata, said. "He wants to know if there are more bad guys in the world, and I don't know how to answer that for him."
For now, the Licatas have put a sign on the door asking people not to ring the bell.
As this south New England town of 27,000 prepares to mourn the 20 children and six adults killed in the school shooting, parents of the youngest survivors are struggling to cope with the aftermath of a massacre that will require many of them to break the news to their child of the death of a teacher or a friend.
"The children eventually will learn about their friends and their teacher, and others that they know. We need to be able to explain to them as best we can," Robert Licata, the boy's father, said.
Aidan doesn't know that his teacher, Victoria Soto, is among the dead. He also doesn't know some of his friends have been killed.
The morning inside the school, when the gunfire started, Aidan said it sounded like "falling hammers."
His teacher, Ms. Soto, moved her first grade students to the other side of the room. Moments later, the gunman -- identified by authorities as 20-year-old Adam Lanza -- was in the doorway.
Soto positioned herself in front of the students, and the gunman shot her, Aidan told his parents.
Aidan and the children had always been told during school drills and by his parents to run if he saw somebody with a gun. So that's what he did.
"They ran past the guy. He standing in the doorway, and they just ran right past him," the boy's father said.
Aidan and the boys ran toward the front door, out of the building and then toward the main road where a woman stopped, picked them up and drove them to the police station.
"He loved his teacher. ...I think he's trying to reassure himself that she's going to be OK," Aidan's mother said. "He keeps saying 'I really hope she is OK. He knows that that she's been hurt. He knows the kids he saw getting shot."
Nick and Laura Phelps also are struggling with what to tell their two children, a first-grader and a third-grader.
They, like many of the parents, were alerted to a possible problem at the school by the district's robocall that instructed them to go to the fire station.
There, they found their children.
"When I saw those teachers, I locked eyes with them separately. If I could go back, I would embrace them," Nick Phelps said, "because I had no idea what they had gone through."
Phelps and his wife planned to attend counseling services being offered in Newtown, and the couple also are seeking guidance from their church pastor.
"We're definitely going to talk to counselors," Nick Phelps said.
By Saturday night, the couple was fairly certain that their children were aware at the least of some of the developments.
"I think they do know more than they let on," Laura Phelps said. "We are going to have to learn what to say before we say it.
The Phelps did not want the names of the children out in the public.
Even those charged with breaking the news to young family members struggled.
At the St. Rose of Lima Catholic Church, Father George Weiss was with the parents of a little boy as they told him his sister had been killed.
"We just told a little boy about his sister, and he asked, 'Who am I going to play with now? I have nobody to play with now.'"
"Excuse me," he said as tears rolled down his face, "it was just so hard."
CNN's Kate Bolduan reported from Newtown, and Chelsea J. Carter from Atlanta. CNN's Soledad O'Brien contributed to this report.