Washington Mayor Vincent Gray joined president Obama's call for action on gun control, mentioning that one of the Navy Yard victims, Arthur Daniels, had already lost his 14-year-old son to gun violence and citing the string of mass public shootings in recent years.
President Obama said: "We Americans are not an inherently more violent people than folks in other countries, we are not inherently more prone to mental health problems, the main difference that sets our nation apart, what's different in America is it's easy to get your hands on a gun."
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Government ministers from the UK, France and China attended the event.
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