NATO said on August 7 that all of the ISAF service members on board were from the US. The incident represents the highest number of US forces killed during a single event since the war on terror began in Afghanistan in late 2001.

“No words describe the sorrow we feel in the wake of this tragic loss,” said US General John R. Allen, the Commander of the NATO-led International Security Assistance Force.

An investigation is underway to determine the exact cause of the crash. Additional details will be provided as they become available.

The incident came after the US began gradual pullout of 33, 000 combat troops from Afghanistan by the end of summer in 2012.

US President Barack Obama offered condolences on August 6 to the families of US soldiers killed in a helicopter crash in Afghanistan. The president also paid tribute to seven Afghans who died in the crash.