US President Barack Obama on Sunday attended a prayer vigil for the victims of the Newtown shooting and vowed to use all his power to make sure that such tragedies would not be repeated.

"We can't accept events like this as routine," Obama said at the vigil. "We as a nation are left with some hard questions. These tragedies have to end, and to end them we must change."

The massacre on Friday left 20 children and six adults dead. The 20-year-old gunman shot his mother at home before entering the school, where he killed 20 children between the ages of 6 and 7. Obama said he would convene a meeting of law enforcers, parents, educators and others in an effort to prevent future tragedies, but did not explicitly call for tougher gun laws.

"Are we really prepared to say that we're powerless in the face of such carnage?" he asked. "That the politics are too hard? Are we prepared to say that such violence visited on our children year after year after year is somehow the price of our freedom?"

"Since I've been president, this is the fourth time we have come together to comfort a grieving community torn apart by mass shootings... and in between, there have been an endless series of deadly shootings across the country," he said "We can't tolerate this anymore. These tragedies must end. And to end them, we must change."

A turning point

How to change had been the topic of countless discussion across US over the weekend. Though hardly known for their ability to agree on much of anything, many guests on Sunday morning talk shows in the United States could agree that the shooting at Sandy Hook Elementary School in Newtown, Connecticut, "could be a turning point" in the United State's approach to gun control. If those murders do not prove to be enough for the United States to tighten gun laws, then what will it take was the question asked repeatedly since the tragedy.

New York City Mayor Michael Bloomberg, a long-time supporter of stricter gun control laws, called on Obama to take the initiative.

"It's time for the president to stand up and lead," Bloomberg said on NBC's "Meet the Press." "This should be his No. 1 agenda. His job is to perform and to protect the American public."

Bloomberg has enforced stricter gun control laws as well as added law enforcement that have contributed to a large reduction in New York's murder rate. Bloomberg also said that if nothing changes in the United States, 48,000 people would be killed by illegal weapons in Obama's second term in office.

Bloomberg: Stop cowering before the NRA

While saying that constitutional right to bear arms should be protected, Bloomberg also outlined how it should be regulated. He called on Obama to take action including: the stricter enforcement of existing laws so that any person who lies on an application for a gun license is criminally charged, the introduction of legislation to ban assault weapons and banning ammunition clips that hold more than 10 bullets, as well as mandatory background checks before a weapon can be purchased.

Bloomberg also criticized politicians who fear the power of the National Rifle Association (NRA), the major US gun lobby group, which he said was being over-estimated by politicians.

"If 27 people killed - 20 children - isn't enough to change the mentality, the psyche, the desires of the American public then I don't know what it will take," he said.

New legal proposals on the horizon

Democratic Senator Dianne Feinstein said she would introduce a new gun control bill on the first day of the next legislative session that will ban assault weapons.

"It will ban the sale, the transfer, the importation and the possession," the California politician said on NBC, adding that the proposed law would also prohibit magazines capable of holding more than 10 bullets. "The purpose of this bill is ... to get weapons of war off the streets."

Such measures seemed to find wide support. Senator Joe Lieberman, an independent, told Fox News that he supported a ban on assault weapons and called for an investigative commission to look at how tragedies like the shooting in Newtown could be prevented.

Mental heath issues cannot be ignored

Democratic Senator Dick Durban compared the effect Friday's school shooting could have to that of the 9/11 terrorist attacks. At that time the nation pulled together and it was possible to get laws changed, he said.

Chris Murphy, a member of the House of Representatives from Connecticut who during the November election was voted into the Senate, warned people from falling for simple solutions.

"There needs to be a conversation about gun control, but also about the way we treat mental illness, also about the culture of violence in this country, which may have contributed to the way in which this very disturbed young man thought," Murphy said on ABC's Sunday broadcast "This Week."

Murphy was not the only one on Sunday's airwaves to call for a wider discussion not only on gun laws, but also on providing access to mental health treatments.

Gun lobby silent following Newtown

In the hours of media coverage about the Newtown shooting, representatives of the gun lobby have had little to say. David Gregory, host of "Meet the Press," said his show invited all 31 senators who expressed their support for gun rights to appear on the show but all declined. Bob Schieffer of "Face the Nation" on CBS said the NRA refused an invitation to appear on the show.

Louie Gohmert, a Republican member of the House of Representatives from Texas, was one of the few conservative, supporters of gun rights who appeared for interviews. He argued that had teachers at Sandy Hook Elementary School also had guns in their offices, they would have been able to kill the 20-year-old gunman.

"I wish to God she had had an M-4 in her office, locked up so when she heard gunfire," he said of the principle at the school who on Fox News, "she pulls it out and didn't have to lunge heroically at him with nothing in her hands but takes him out and takes his head off before he can kill those precious kids."