Marines killed in mid-air collision

Updated at 5:13 am on 24 February 2012

Seven United States Marines have been killed in a collision between two helicopters in Arizona.

The mid-air accident happened near the city of Yuma during a training exercise on Wednesday night.

An investigation is being held into how it happened.

The Marine Corps said the collision occurred in a remote portion of the Yuma training range complex.

A Marine spokeswoman told CNN that helicopter teams use the area to because it mimics conditions in Afghanistan.

Next story in World: Hacking claim lodged by Cherie Blair