The comments by the National Rifle Association came exactly a week after a gunman killed 26 people, including 20 young children, and as pressure mounts in Washington for more measures against gun violence.
"The only thing that stops a bad guy with a gun is a good guy with a gun," said the NRA's executive vice president, Wayne LaPierre, at a Washington news conference.
At least two protesters broke up his announcement, despite tight security. One man held up a large red banner that said "NRA killing our kids". The protesters were taken away by security, shouting that guns in schools were not the answer.
The 4.3 million-member National Rifle Association may be facing its toughest challenge in the wake of national horror over last week's killing of children, many of them shot multiple times and at close range with a high-powered rifle.
Referring to the 20-year-old responsible for last week's shooting, Mr LaPierre said "the next Adam Lanza" was planning an attack on another school.
He blamed the media, video games, films and music videos for exposing children to a violent culture.
"In a race to the bottom, many conglomerates compete with one another to shock, violate, and offend every standard of civilised society, by bringing an even more toxic mix of reckless behaviour and criminal cruelty right into our homes," he said.
As "some have tried to exploit tragedy for political gain, we have remained respectfully silent," he added.
Mr LaPierre also announced former Representative Asa Hutchison will lead an NRA programme that will develop a security plan for schools that relies on armed volunteers.
The NRA largely disappeared from public debate after the shootings, choosing atypical silence as a strategy as the nation sought answers after the rampage. The organisation temporarily took down its Facebook page and kept quiet on Twitter.
Since the Newtown shooting, President Barack Obama has demanded "real action, right now" against gun violence and called on the NRA to join the effort.
His administration has been moving quickly after several congressional gun-rights supporters said they would consider new legislation to control firearms.
Mr Obama has said he wants proposals on reducing gun violence that he can take to Congress by January, and has put Vice President Joe Biden, a gun-control advocate with decades of experience in the Senate, in charge of the effort.
The president said in a video released early yesterday the White House has received an outpouring of support for stricter gun laws over the past week. "We hear you," he said.
A We the People petition on the White House website allows the public to submit petitions. Nearly 200,000 people have urged Mr Obama to address gun control in one petition, and petitions related to gun violence have amassed more than 400,000 signatures.
At the same time, however, gun shops across the country have reported higher sales, including of assault weapons. A spike in gun sales is not uncommon after mass shootings.
Mr Obama has already asked Congress to reinstate an assault weapons ban that expired in 2004 and pass legislation that would end a provision that allows people to buy firearms from private parties without a background check.
The NRA response came after church bells rang out up and down the East Coast of the US at 9.30am in memory of victims of the nation's second-deadliest school shooting.
Churches as far south as Florida and at the National Cathedral in Washington DC rang their bells.
Meanwhile, four people including the gunman were killed and three Pennsylvania state troopers wounded yesterday during a shooting in Frankstown Township, Pennsylvania.
The gunman, two other men and a woman were killed, according to a local newspaper. . The troopers were reportedly wounded in a shootout with the suspect.