Washington ( CNN ) -- The Afghanistan battle that resulted in a rare fatality for a classified Army unit pitted U.S. troops against waves of insurgents who attacked from bunkers and caves , a U.S. military official said Wednesday . American forces had to be reinforced several times during the two-day firefight in southeast Afghanistan 's Paktika province , said the official , who declined to be named because he was discussing the Army 's Special Operations Command . The sole U.S. fatality in the attack was Army Master Sgt . Benjamin A. Stevenson , a highly decorated member of one of the Army 's special mission units . The death in combat of a soldier from one of these highly trained units is rare , with the last occurring nearly a year ago , the official said . The classified units are sometimes publicly referred to as Delta Force , the Army equivalent of the Navy SEAL team that killed al Qaeda leader Osama bin Laden in May . In the Paktika raid , U.S. and Afghan troops attacked an insurgent encampment under cover of darkness last week , killing nearly 80 foreign fighters -- mostly Arabs and Chechens brought into Afghanistan from Pakistan , the military official said . But as they searched the site in the daylight , they were attacked by two more waves of insurgents who came out from underground bunkers and caves . Additional U.S. forces were called in several times as reinforcements as the firefight stretched on . Get latest news at Afghanistan Crossroads blog . Stevenson , 36 , from Canyon Lake , Texas , was on his 10th tour of duty in the war zones of Afghanistan and Iraq when he was killed Thursday . The military official said he died shortly after being evacuated from the battlefield , but the Pentagon has disclosed no other details . The story behind his death offered a rare glimpse into the work of U.S. special operations units . The target of last week 's raid was a camp full of fighters from the so-called Haqqani network , which is responsible for many recent attacks in Afghanistan and is closely tied to al Qaeda . The presence of so many foreign fighters among an insurgent group that typically relies on local Afghan and Pakistani populations for manpower is a worrisome trend , according to a second U.S. military official . `` This is how they are expanding their capabilities , '' the official said .
Afghan insurgents emerged from caves and bunkers in the 2-day battle . The battle led to a rare tactical victory for a classified U.S. Army unit . The U.S. military was tight - lipped about special ops operations .