WASHINGTON (AP) — Harold J. Greene, the two-star Army general who became the highest-ranking U.S. military officer to be killed in either of America’s post-9/11 wars, was an engineer who rose through the ranks as an expert in developing and fielding the Army’s war materiel. He was on his first deployment to a war zone.

Greene was killed Tuesday when a gunman believed to be an Afghan soldier opened fire at a military academy near Kabul. More than a dozen other coalition soldiers were wounded, including about eight Americans, according to early accounts of the attack. It was among the bloodiest insider attacks of the war in Afghanistan.