A veteran American photojournalist and a translator working for National Public Radio were killed while accompanying Afghan troops in southern Afghanistan on Sunday, according to NPR and military officials.

NPR's David Gilkey, 50, and Afghan translator Zabihullah Tamanna, 38, were in an Afghan army Humvee travelling between the provincial capital of Helmand province, Lashkar Gah, and Marjah when their vehicle was struck by an 82mm rocket during a Taliban ambush, Shakil Ahmad Tasal, a spokesman for the Afghan army's 205th Atal Corps told Reuters.

The attack occurred around 2:30 pm local time and also killed the vehicle's driver, an army soldier, said Mr Tasal.