A lone police cruiser outside Columbine High School was the only outward reaction Friday to an even deadlier attack at a Connecticut elementary school.
But in a state that was rocked by the 1999 Columbine school massacre and the Aurora movie theater shooting less than six months ago, Friday's shootings renewed debate over why mass shootings keep occurring and whether gun control can stop them.
"Until we get our acts together and stop making these ... weapons available, this is going to keep happening," said an angry Tom Teves, whose son Alex was killed in the theater shooting last July in the Denver suburb of Aurora.
Teves was choked up as he answered a reporter's call Friday. A work associate of his lives in Newtown, Conn., where a gunman killed 26 people, including 20 children, at Sandy Hook Elementary. The connection chilled and angered him.
The 20-year-old killer, identified by a law enforcement official as Adam Lanza, carried out the attack with two handguns. A .223-caliber rifle was found in the back of a car.
The official was not authorized to speak on the record about the unfolding investigation and spoke on the condition of anonymity.
The shooting has once again stoked the never-ending debate over gun control laws.
This week, Colorado Gov. John Hickenlooper generated a storm of debate after declaring that it was time to start talking about gun control measures.
After Friday's school shooting, Hickenlooper told reporters there's no use waiting until news coverage fades.
"We can't postpone the discussion on a national level every time there's a shooting. They're too often," he said.
A visibly emotional President Barack Obama seemed willing to renew debate, calling for "meaningful action" to prevent similar shootings.
New York Mayor Michael Bloomberg, an advocate of greater limits on guns, responded directly to the president's remarks: "Calling for 'meaningful action' is not enough. We need immediate action. We have heard all the rhetoric before."
Also Friday, Mark Kelly, the astronaut husband of former U.S. Rep. Gabrielle Giffords, who was shot in the head during an attack that killed six people in Tucson, Ariz., last year, said the Connecticut shooting should "sound a call for our leaders to stand up and do what is right."
"This time our response must consist of more than regret, sorrow, and condolence," Kelly said on his Facebook page, calling for "a meaningful discussion about our gun laws and how they can be reformed and better enforced to prevent gun violence and death in America."
Tom Sullivan, whose son Alex also died in the Aurora theater shooting, welcomed the discussion. Sullivan and his wife spent part of the morning making sure relatives who live in the area were OK.
Sullivan said mental health, not gun control, is a more pressing concern.
"We all need someone in our lives to care," Sullivan said. "If we see a friend, a colleague, a co-worker and they're having a hard time, we need to reach out."
Sean Graves, who as a student was wounded at Columbine, said he was "disgusted" by the shootings but he didn't believe laws can prevent such violence.
If people "want to find a way to harm people, they're going to find a way to do it," Graves said.
Former U.S. attorney Troy Eid, who was part of a government panel that examined the Columbine shooting, said more must be done to examine what motivates such criminals.
"It's something that's become part of our culture. We have to study it and see what we can do to prevent it," Eid said.
Some shoppers interviewed at Oregon's Clackamas Town Center, where a gunman killed two people Tuesday before killing himself, had similar reactions.
"We need to pay more attention to the people close to us, because I think there's a lot of signs prior to things," said shopper Sierra Delgado of Happy Valley, Ore.
Mental health screenings alone aren't enough, other Colorado shooting survivors said.
Tom Mauser, who became a gun control advocate after his son Daniel was killed at Columbine, urged officials to stop "playing defense" on gun control.
"Let's not say once again, 'Oh, this is not the right time to talk about it.' It is the right time to talk about it.
"We are better than a nation that has people killing children and has people cowardly shooting people in shopping malls and schools and nursing homes. We're better than this."
Such emotional appeals didn't come only from gun control supporters. Friday's responses from both sides foretold a heart-wrenching debate.
"They're going to use the bodies of dead children to push their agenda," predicted Dudley Brown of the Denver group Rocky Mountain Gun Owners.