(BEGIN VIDEO CLIP)
STEPHANOPOULOS (voice-over): This morning from Newtown, Connecticut, a special edition of "This Week."
Tragedy at the elementary school.
(UNKNOWN): Everything was just normal, and then it all just changed.
STEPHANOPOULOS: Twenty-seven killed, most in the first grade.
(UNKNOWN): She is (OFF-MIKE) I'm so blessed to be her dad.
(UNKNOWN): Evil visited this community today.
STEPHANOPOULOS: Evil met by bravery.
(UNKNOWN): I said there are bad guys out there now, and he is the good guy.
STEPHANOPOULOS: This morning, we remember those lost.
OBAMA: They had their entire lives ahead of them -- birthdays, graduations, weddings.
STEPHANOPOULOS: And ask, why?
(UNKNOWN): This was not God's plan. This was a man who has serious issues in his life.
STEPHANOPOULOS: And now, as America grieves, how should our leaders respond? What can all of us do to stop this senseless violence?
(UNKNOWN): We will find a way to heal.
STEPHANOPOULOS: We'll get to the heart of those questions right now.
ANNOUNCER: From ABC News, this is a special edition of "This Week" with George Stephanopoulos. Tragedy at the elementary school, reporting from Newtown, Connecticut, George Stephanopoulos.
(END VIDEO CLIP)
STEPHANOPOULOS: And good morning from the library at Newtown Middle School. This is where the 20 children killed at Sandy Hook Elementary would have continued to learn and grow, just down the road from Newtown High School, where President Obama will come tonight to comfort the families, thank the first responders, and console the community still in shock.
The heartbreak here is magnified by the age of almost all the victims, little children, 6 and 7 years old, all in just the first grade.
Overnight, the shooter's father, Peter Lanza, released his first public statement: "We are in a state of disbelief and trying to find whatever answers we can. We, too, are asking why."
And this morning, America is honoring the victims. Today, every NFL team will observe a moment of silence before the games. The Giants and Patriots will wear special decals on their helmets.
Our guests and experts are standing by for a conversation about what happened and why, to discuss what it means to take meaningful action -- that's President Obama's phrase -- and to reason about a shattering moment of mindlessness.
We begin with the latest on the investigation. With me now, Brian Ross, our chief investigative correspondent. And, Brian, investigators are beginning to piece together what happened in that terrifying 10 minutes in the school.
ROSS: That's right, George, they say they are making good progress in knowing much of the how, although less of the why of the stunning crime. In particular, they are focusing on the weapons used. There were three weapons recovered, two handguns, and a semiautomatic assault-style rifle that authorities believe was owned actually by Adam Lanza's mother, Nancy. Her friends say she was a gun enthusiast who bought the weapons for self-defense when she was divorced and lived in a large home by herself and often took her sons, her friends say, to a nearby firing range for target practice.
STEPHANOPOULOS: So they confirm that the weapons belonged to her, but there had also been some reports, at least one report, I believe, in the L.A. Times, that the shooter may have tried to buy a weapon recently.