The National Rifle Association says armed police officers should be present in every school in America, as protests interrupt a news conference following the Connecticut shootings.
NRA chief executive Wayne LaPierre claimed that the 26 innocent victims at Sandy Hook elementary school could still be alive if Adam Lanza had been confronted by gunmen.
He also blamed the media for promoting violence through video games and said it demonised lawful gun owners.
Speaking today for the first time since the shootings, he said: “The only thing that stops a bad guy with a gun is a good guy with a gun.
“The NRA is going to bring all its knowledge, all its dedication and all its resources to develop a model national school shield emergency response programme for every school in America that wants it.”
He speculated that another school gunman was waiting in the wings and said every single school in America should immediately deploy a protection programme, including armed security.
Mr LaPierre was interupted on two occasions by protesters holding up signs saying: “NRA killing our kids” and “NRA blood on your hands”.
It came after Connecticut Governor Dannel Malloy called for residents of his state to observe a moment of silence at 9:30 a.m. (2.30pm GMT) today, a week after the shootings, and his fellow governors from Maine to Kansas followed suit.
The national cathedral in Washington rang its bell 28 times as part of an interfaith memorial.
“We have the moral obligation to stand for and with the victims of gun violence and to work to end it,” said Reverend Gary Hall, dean of Washington national cathedral, who called on Americans to pray “that we may have courage to act, so that the murderous violence done on Friday may never be repeated”.
The company that operates the Nasdaq stock exchange observed a moment of silence at 9:30 a.m., although markets opened trading at that time as usual.
The rampage, in which 28 people died, including 20 children and the gunman, has sparked new discussion on tightening gun laws, a thorny political issue in the United States, which has a strong culture of individual gun ownership.
It comes as Vice President Joe Biden convened a White House task force to search for ways to quell gun violence.
With funerals for a half-dozen victims on Thursday, services have now been held for more than half of the 27 people shot and killed last Friday by 20-year-old man Adam Lanza, who carried out his attack armed with an assault rifle.
Laws restricting gun ownership are controversial in the United States, a nation with a strong culture of individual gun ownership. Hundreds of millions of weapons are in private hands.
About 11,100 Americans died in gun-related killings in 2011, not including suicides, according to preliminary data from the US Centres for Disease Control and Prevention.
Adam Lanza used guns that were legally purchased and registered to his mother Nancy, his first victim in last week’s attack.