ABC News has learned that the bomber was invited into the heavily guarded camp as a possible informant, but wasn't searched.
a href="http://abcnews.go.com/International/wireStory?id=9453232"target="external">The bomber, who was dressed in an Afghan military uniform, was escorted to the gym for a meeting with a senior CIA debriefer, according to intelligence sources familiar with the incident. When the bomber was brought into the gym he blew himself up, killing seven and seriously injuring an additional six officers who had gathered there to wait for him.
The attack targeted some of the CIA's most important assets in the fight against the Taliban and al Qaeda, officers who collected intelligence and conducted paramilitary operations in both Afghanistan and Pakistan. While it's unlikely the officers spent much time in Pakistan, they almost certainly contributed to the drone program that has targeted al Qaeda's senior leadership living in the Pakistani tribal areas.
"This is a tremendous loss for the agency. The agency is a relatively small organization, and its expertise in al Qaeda is even a smaller subset of that overall group," says Michael Scheuer, the former head of the CIA unit that searched for Osama bin Laden. "We collect information that enables the military to go after our primary targets or to better defend itself. So to the extent we lose the ability to do that -- the experienced personnel to do that -- it harms not only the agency, but it harms the ability of the military to operate effectively in the area."
ABC News' Kirit Radia and Richard Esposito contributed to this report