Police plan to trace the firearm used in the shooting. Sources describe the weapon as a semiautomatic pistol with an extended clip.
DUPNIK: He probably would have shot other people had he not been tackled by two people.
THOMAS: Saturday's shootings reflect a disturbing trend. Mass shootings have become commonplace since the Virginia Tech massacre in 2007. There have been dozens of incidents where three or more people have been fatally wounded. Hundreds have died.
The image is always the same: innocent lives lost; police tape; sirens. And Loughner, like so many suspects before him, young, angry, troubled, and with a gun.
For "This Week," I'm Pierre Thomas in Washington.
AMANPOUR: There have also been so many stories of courage and fortitude around this tragedy, the person who tackled Loughner to the ground and also a young intern, 20-year-old Daniel Hernandez, who held Congresswoman Giffords as he saw her go down, running towards the gunfire. He joins us right now on the phone.
Daniel Hernandez, thank you for joining us. It must have been an incredible moment as you ran towards the gunfire when it all broke out. Tell me what happened yesterday.
HERNANDEZ: Of course, because there is a pending investigation, we're trying to make sure that everything that we talk about is just details regarding the incidents after the shooting.
Yesterday, I was helping Congresswoman Giffords at Congress on Your Corner, which was an event to try and meet with her constituents. And before the shooting happened, we had a lot of excited constituents who were very happy to get the opportunity to speak to their congresswoman, because everybody was going to get a chance to speak with her one on one for about three to five minutes.
However, as you know, there was a tragic shooting where we ended up having 19 victims and 6 fatalities.
But when the shooting started, my first instinct was to try and make sure that the congresswoman and her staff were OK. I have limited experience in triage and training, so when I heard gunshots, my first instinct was to head towards the congresswoman to make sure that she was OK.
Once I saw that she was down and there were more than one victim, I went ahead and started doing the limited triage that I could with what I had, so checking for pulses and then also making sure that -- covering and applying pressure to the wounds.
AMANPOUR: It must have...
HERNANDEZ: Yeah, go ahead.
AMANPOUR: It must have been a terrifying experience for you. And then to have the presence of mind to know what to do -- and you saw her head was severely wounded, is that correct?
HERNANDEZ: Yes, yes. When this happened, I kind of just shut off all emotion, because I knew I wouldn't be any good to anyone if I had a breakdown or if I ran away or if I did anything other than try and help those who needed help, so that was the congresswoman and her staff and several constituents.
AMANPOUR: And once -- you were able to hold her, you got bandages. There were really sort of pieces of cloth, I think, that were given to you. What then happened? How long did it take before the ambulance or the airlift came?