The body of Maj. Gen. Harold Greene is being prepared to be flown to the United States via Dover Air Force Base in Delaware, NATO officials said.
An Afghan soldier shot and killed the two-star general Tuesday while Greene was visiting a military university on a base west of Kabul.
The soldier, who went by the single name of Rafiqullah, also wounded about 15 U.S. and coalition forces, including a German general and two Afghan generals, before he was killed.
"Our thoughts and prayers are with Maj. Gen. Greene's family, and the families of our soldiers who were injured," NATO said. "These soldiers were professionals, committed to the mission."
CBN Contributor and former Army Ranger Chuck Holton spoke more about this incident and how common these insider attacks are. Click play for more insight.
An Afghan military official told the Associated Press that Rafiqullah hid in a bathroom before the assault and used a NATO machine gun in his attack. The motive for the attack remains unclear.
The unnamed official said that Rafiqullah, in his early 20s, had joined the Afghan army more than two years ago.
The official said that before the assault he had just returned from a patrol with others who turned in their NATO-issued weapons on arrival. But Rafiqullah kept his and hid in a bathroom. He opened fire when Greene and the other generals walked into view. There is no indication that Greene was specifically targeted.
Greene is the highest-ranking American officer killed in combat in the wars in both Afghanistan and Iraq.
Another "insider" attack occurred late Tuesday in the Uruzgan provincial capital of Tirin Kot. An Afghan police officer there killed seven of his colleagues at a checkpoint.
These insider attacks in Afghanistan rose sharply in 2012 with more than 60 coalition troops killed.
Last year, the number declined sharply with just 16 deaths. The attacks are sometimes claimed by the Taliban as proof of its infiltration but others are attributed to Afghans who are resentful of the continued international presence in their country.
One concern with the attacks is that they threaten to shatter all trust between Afghan and allied forces.
The U.S.-led military coalition in Afghanistan is moving towards withdrawal which is expected to be complete by the end of the year.