2 die in U.S. Embassy shooting incident in Kabul

Kabul, Afghanistan (CNN) -- An Afghan employee killed a U.S. citizen and wounded another at an annex of the American Embassy in Kabul, Afghanistan, a spokesman said Monday.

The Afghan employee was the lone gunman and was killed, according to Gavin Sundwall, a U.S. Embassy spokesman.

"The motivation of the attack is still under investigation," he said. The shootings took place Sunday evening.

The wounded American was evacuated to a military hospital with non-life threatening injuries.

The annex area is known as a place where embassy personnel both live and work, some in intelligence operations. A CIA spokeswoman declined to comment on the attack.

Afghanistan has been the site of several high-profile attacks of late, including strikes at the NATO headquarters and the U.S. Embassy in Kabul and the assassination of former Afghan President Burhanuddin Rabbani. Rabbani had been leading efforts for reconciliation talks.

U.S. Secretary of Defense Leon Panetta contended Thursday that such attacks represent a strategy shift by the Taliban, the conservative and militant group that has been waging a years-long fight in the war-torn nation.

"We judge this change in tactics to be a result of a shift in momentum in our favor and a sign of weakness in the insurgency," Panetta said at a Senate Armed Service Committee hearing.

He added that "the insurgency has been turned back in much of the country, including its heartland in the south, and Afghan National Security Forces are increasingly strong and capable."

Mike Mullen, the outgoing chairman of the Joint Chiefs of Staff, testified then that he felt Pakistan is "exporting" violence to Afghanistan. He described the Haqqani terrorist network as "a veritable arm of Pakistan's intelligence" -- an assertion that Pakistani officials later strongly denied, even as it admitted the country does have contacts with the group.

August was the deadliest month for U.S. forces in Afghanistan since the conflict began. Seventy-one American troops died that month, including 30 killed when insurgents shot down a helicopter August 6 in the eastern central province of Wardak.

The surge in U.S. deaths comes as NATO is drawing down and handing over security control to national forces. Some 10,000 U.S. troops are scheduled to depart by year's end, with all U.S. military personnel out of Afghanistan by the end of 2014.