The husband of the US politician Gabrielle Giffords, who was shot in Arizona, has called for action on America's gun laws following the latest mass shooting.
As America deals with the aftermath of the shooting at Sandy Hook Elementary School, Captain Mark Kelly, a Nasa astronaut, wrote on his Facebook page that tightening the gun controls could wait no longer and called on politicians to act now.
He said: "As we mourn, we must sound a call for our leaders to stand up and do what is right."
He added: "The children of Sandy Hook Elementary School and all victims of gun violence deserve leaders who have the courage to participate in a meaningful discussion about our gun laws - and how they can be reformed and better enforced to prevent gun violence and death in America. This can no longer wait."
Barack Obama wipes away a tear as he calls for "meaningful action" His wife was one of the people shot by Jared Loughner in Arizona in 2011. She survived with serious head injuries but six others were killed in the attack.
Barack Obama hinted at the possibility of gun law reform following the shooting in Connecticut, signalling it was time to come together to take meaningful action, "regardless of the politics".
There have been 61 mass murders involving firearms since 1982.
The most recent, where Adam Lanza shot dead 27 people on Friday, ranks as the country's worst school shooting.
Of all shootings, it is second in its gravity only to the Virginia Tech shooting in 2007, which claimed 32 lives.
A call for action at the White House vigil for the victims of the shooting Already there have been protests outside the White House calling for reform of America's liberal gun laws.
Michael Moore, the director of Bowling For Columbine, a documentary which explored America's relationship with guns, tweeted: "Too soon to speak out about a gun-crazy nation? No, too late. At least THIRTY-ONE school shootings since Columbine."
He added: "The way to honour these dead children is to demand strict gun control, free mental health care, and an end to violence as public policy."
But with the right to bear arms enshrined in the second amendment to the US constitution and an increasingly strong gun lobby in the National Rifle Association, it is thought to be unlikely that will take the form of an outright ban.
Part of the problem with the US gun laws is that they vary widely between different states.
Connecticut, the state at the centre of the latest shooting, has the fourth strongest gun laws in the country, the US political commentator Charlie Wolf, told Sky News.
Yet Lanza, who it has been reported has a history of mental health, managed to amass an arsenal of at least six lethal weapons.
Two handguns and semi-automatic rifle found at the scene appeared to be legally purchased by the mother of the mass shooter.
Cho Seung-Hui killed 32 at Virginia Tech - America's most deadly shooting Mr Wolf said the Sandy Hook shooting would not lead to an outright ban on gun ownership and that there were other issues which needed to be addressed, such as mental health.
He said: "I'm sure if this guy really wanted to he would have found guns elsewhere. It didn't stop Derrick Bird in this country (UK)."
He said that the right to bear arms was enshrined in the constitution but that it was possible the law could be strengthened to make sure people who shouldn't own guns couldn't buy them.
On top of the differences in gun laws across the states, the federal government regulates very little.
The so-called Brady law, signed into law by President Bill Clinton in 1993, requires federal background checks on firearm purchasers in the United States.
It is intended to detect any potential red flags in an individual's criminal and mental health history.
But 40 per cent of arms sales are not affected by the law, because they take place between private individuals, through websites, or at gun show stands. These sales are not regulated by the federal government.
Loughner, who carried out the attack that wounded Ms Giffords, obtained the green light from the background check system before purchasing his guns.
He was cleared even though he was suspended from school for misconduct and had a history of drug use.
Gun ownership in the US is now at an all-time low and there is a suggestion that the public increasingly supports some gun control measures.
A recent CCN/ORC poll found a majority supported background checks and a ban on semi-automatic weapons.
Perhaps the killing of 20 children all aged under 10 will come to mark the beginning of a discussion that could lead to a rethink on America's gun laws.
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