Gun laws in Nevada are among the most relaxed in the United States, where 59 people were shot dead and more than 500 more injured at a country music festival last night.
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You don't need a permit to have a rifle or shotgun, and you can carry them around, including into bars and even while having a drink.
But as history shows, many massacres have happened all across America.
Thirty-one percent of the world's mass shootings have been carried out in the US, where there are about 300 million guns - one for every man, woman or child.
So far this year, there have been more than 46,000 gun-violence incidents.
New Zealand's US ambassador Scott Brown says it's too early to tell whether the deadliest massacre in the country's modern history will prompt President Donald Trump to consider tighter gun regulations.
"Certainly, he's one person that can help... it's really up to the voters to elect people that they feel can speak on their behalf and change those laws," Mr Brown told Three's The Project.
"But this just happened yesterday and with respect, it's been tough to digest all of the new facts and information. So I can't speak for the president, but I'm hopeful that this will trigger a debate in the United States to have a top-to-bottom review of every law dealing with firearms and then let the people decide where they want to go with this."
Mr Brown says he used to be in favour with the National Rifle Association (NRA), but had a falling out with it, when he slightly changed his view on gun laws.
"I'm a gun owner - I have two guns, I respect firing, I enjoy target practice - but I voted to continue on with the expansion and continuation of the assault weapons ban in Massachusetts.
"So I went from an A-plus to a C-minus rating [with the NRA]. It's cool, I don't think I lost because of that... but I felt that their true colours came out, because I am a gun owner, and respect the right for people to carry and bear arms."
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