A father who shot dead a gunman at his two daughters' school in the US state of Oregon has described "hearing children pleading for their lives" and his anguish over those he could not save.
Three students and a teacher were killed by a 16-year-old former student at Silver Rail Elementary School earlier this month. The attacker was then killed by parent Kaylub Giamanco.
"I want to apologise for not saving their babies," Giamanco, who has been hailed as a hero, said of his thoughts for the parents of the children killed in an interview with Oregon Public Broadcasting (OPB) that aired on Friday.
"The gratitude for saving people's children is awesome, but there were ones that I didn't save."
Giamanco, 36, said he wanted to meet the victims' families and "cry with them and hold them".
He credited a teacher who fought the attacker with giving him the chance to intervene without losing his own life.
"I would love to give her a hug because that's a real true hero," he said.
The students who were killed were all boys, aged five, eight and 11. They were among six people in total who were shot in a classroom at the school, police said. Alongside the teacher who was also killed, another child and a teacher were wounded.
Giamanco told OPB the day of the attack began with breakfast and packed lunches. He and his wife spent extra time getting their daughters ready because it was school picture day.
The carpenter had taken lunch to work but decided to go home to eat with his wife instead. That decision brought him past the school as the attack began.
He initially wondered whether someone carrying a long gun was playing a prank. Then he saw him fire at a pickup truck and head towards the school.
Giamanco retrieved a handgun from his vehicle and called emergency services.
"I said, 'I'm sorry, I have to go in. People are going to die,'" he told the broadcaster.
He followed the attacker, who shot through the school's locked glass doors. Hearing children pleading for their lives and more gunfire, Giamanco crawled towards the building.
"I told myself this is probably the last thing that I'm ever going to do," he said.
Giamanco crawled through a shattered window and reached the classroom, where a teacher was struggling with the gunman. He opened the door and fired.
Giamanco told OPB he fired again when the attacker reached for his weapon. He then placed his own gun on the ground and raised his hands as an officer appeared.
He described feeling like the "last line of defence" between the children and the gunman and said he "was supposed to be there" that day.
Afterwards, he called his wife to say he would not be home for lunch and that she needed to get to the school immediately. He then called his mother to tell her what had happened.
"Mum, I just had to take the life of what I think is might be a child because he ran into my daughter's school with a gun," he said.
Police identified the gunman as Griffin J John II - a former pupil who had attended special education classes at the school. His motive remains under investigation.
Police said the teacher who confronted the attacker had thrown her phone at him, tackled him and fought to take his shotgun. Bend Police Chief Mike Krantz said she "almost certainly helped prevent more bloodshed".
The youngest victim was Rhoam Summer, 5. His father said the family was "broken and lost".
Megan Lambert, 25, the teacher who was killed, was working in what her family described as her "dream job".
"She always fought for the underdog and those with special needs," they said.
The other two boys have not been publicly named at their families' request.
The injured teacher has been named as Becky Drury, 54. She said in a statement shared with US media that the gunman shot her as she tried to shut her classroom door.