Newtown, Connecticut (CNN) -- Amid the chaos that first-responder Ray Corbo witnessed on Friday, there is one image that he will never forget.
It isn't the woman who was taken to the hospital after being shot in the foot at Sandy Hook Elementary. It isn't the police officer he saw leaving the school's interior covered in someone's blood.
What will haunt Corbo forever is the memory of parents lined up outside the firehouse just a few hundred feet away from the school, waiting to pick up their children.
"As the children were coming down the street, little by little, classroom by classroom all holding hands, parents were claiming their children," says Corbo, the first assistant fire chief at Newtown Hook and Ladder No. 1. "After a little while, once they claimed their kid and signed them out ... they left.
"There were some sticking around and that's when we realized that they're probably not going to be leaving. They're gonna get the confirmation soon enough that they're not gonna be grabbing their child and hugging them and taking them home."
Corbo's voice is steady, but his eyes glisten. "Their life is changed forever."
Corbo, along with Rob Manna, the department's chief engineer, were among the first responders to Friday's school massacre of 20 children and six adults.
Manna was working less than half a mile from the school in the center of Sandy Hook when he got the call.
"I was there very soon," he says. At the time, he says, he had no idea what he was walking into.
Corbo and Manna were assigned outside the school, to an emergency triage area that didn't end up being used.
Despite their combined nearly half-century of experience, the two men say nothing could have ever prepared them for what they have now personally experienced.
"You get the initial dispatch, and you really don't know what you're coming in to, but for the most part, you're ready for it," Corbo says. "But this time, it was not the case ... if you think you're ready for this, you're not.
"Very early on, it was determined that this was bad -- really, really bad."
Police and paramedics, some clad in body armor and bulletproof vests, entered the school cautiously.
"They had to find out if anyone survived ... if there was anyone to take care of," Manna says.
Outside, it was mass confusion. Phone calls and text messages spread nearly faster than reports on police radios.
"It was chaos down there. Parents were coming from all directions. You could see the panic in everybody's face, because they have no idea what they're coming into," Corbo says. "They were panic-stricken and trying to get to their children, but they were stopped."
At the nearby firehouse, he says, he saw parents waiting in line for hours to pick up their children.
"And there's no more kids around to take home," Corbo says. "And you know, it's bad. They're gonna get some bad news. I'm sure they knew at that point, but there's that shred of hope there's somebody hiding in closet or some kid they missed, but ultimately that wasn't the case."
Corbo is a father to a first-grader and, had they not moved two years ago, his 7-year-old son Joey would have attended Sandy Hook Elementary.
When he returned home Friday, the former Marine did what many of the parents outside the school could not.
"'I love you' was the first thing I said," Corbo recalls. "And we hugged a lot. Of course, he's 7 years old, so a hug in the morning is fine, and before you go to bed, but getting hugged all day long, he's wondering what the heck's going on.
"He'll understand someday."
Manna says his grieving will come later. "For now, (I've) gotta be strong."
Today, Newtown is awash with emblems of tragedy: an enormous American flag, starkly silhouetted against the sky, flies at half-staff in the middle of Main Street.
Just east, on the road that leads towards Sandy Hook Elementary, a host of 27 wooden angel statues sing a silent chorus on the roadside, a tribute to those who died Friday. Police say Adam Lanza shot and killed his mother at the home they shared, before carrying out the rampage at the school where he left 26 dead and also shot and killed himself.
A small bright note is the overwhelming support Newtown has been receiving from around the country and the world -- including truckloads of teddy bears that firefighters are distributing to children's groups, schools and churches..
"The community will go on," Corbo says. "We have to. There are still a lot of children in this town waiting for Christmas to come. You have to move on. For their sake, it's gotta be back to normal as soon as we can get it."
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