The US military says it has no reason to doubt the authenticity of a video leaked through the whistleblower website WikiLeaks showing a US military attack on a group of civilians in Iraq.br br In the 2007 attack, a US military helicopter fired on a group of Iraqis, killing 12 civilians, according to the website, including two employees of the Reuters news agency.br br The footage from a helicopter cockpit also shows a man stopping to help the injured, but he too is shot dead.br br In an Al Jazeera exclusive, Omar al-Saleh reports on the man's children, who were injured but survived the attack.