LITTLETON, Colo. » 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 27 people were killed, including 18 children, at Sandy Hook Elementary. The connection chilled and angered him.

The Connecticut gunman was reported to have used a .223-caliber rifle, although it wasn’t immediately clear what type. Weapons that use the .223 caliber ammunition can range from assault-style rifles similar to the AR-15 semi-automatic used by James Holmes in Aurora in the July 20 shooting that killed 12 people and wounded 70 to hunting rifles.

The gunman in the recent Oregon shopping mall shooting also used an AR-15, and the Washington, D.C.-area snipers John Allen Muhammad and Lee Boyd Malvo used a .223-caliber Bushmaster, both largely civilian versions of the military’s M-16.

Versions of the AR-15 once were outlawed under a U.S. assault weapon ban in 1994. That prohibition expired in 2004 and Congress, in a nod to the political clout of gun enthusiasts, did not renew it.

This week, Colorado Gov. John Hickenlooper generated a storm of debate after declaring that it was time to start debating gun control measures. Hickenlooper specifically mentioned the AR-15.

"When you look at what happened in Aurora, a great deal of that damage was from the large magazine on the AR-15. I think we need to have that discussion and say, ‘Where is this appropriate?’" Hickenlooper said Wednesday.

After Friday’s school shootings, 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 Obama seemed willing to renew debate, calling for "meaningful action" to prevent similar shootings.

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.

"Clips that hold 50 bullets? The only animal you’re after with that is man. There is no other reason. That’s what that is used for. My question to those people is, ‘Why do you need a clip that holds 50 bullets?’" Sullivan said in a phone interview.

But 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."

Some shoppers interviewed at Oregon’s Clackamas Town Center, scene of the Tuesday mall killings, 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.

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Associated Press writers Brian Skoloff in Phoenix; Terrence Petty in Portland, Ore.; and P. Solomon Banda, Dan Elliott, Ivan Moreno and Kristen Wyatt in Denver contributed to this report.