Man in Afghan uniform kills 3 U.S. troops

• A suicide bomb attack kills four Americans in Afghanistan's Kunar province
• Among the dead are senior members of the 4th Brigade Combat Team, 4th Infantry Division
• Also killed is a USAID Foreign Service Officer, the State Department says

(CNN) -- A suicide bomb attack in Afghanistan's volatile Kunar province has killed a U.S. foreign service officer and three senior American military leaders, officials said late Thursday.

Killed in the explosion on Wednesday was Army Command Sgt. Maj. Kevin J. Griffith, the senior enlisted soldier of the 4th Brigade Combat Team, 4th Infantry Division from Fort Carson, Colorado, the Department of Defense said.

Also killed in the blast were Army Maj. Thomas E. Kennedy, 35, of West Point, New York, and Air Force Maj. Walter D. Gray, 38, of Conyers, Georgia, the Defense Department said.

Kennedy served on the brigade staff, while Gray was a flight commander attached as a liaison to the brigade, according to their respective service records.

Griffith, 45, of Laramie, Colorado, was the brigade's senior ranking non-commissioned officer, the Defense Department said.

An American USAID Foreign Service Officer, Ragaei Abdelfattah, and an Afghan interpreter were also killed, the State Department said.

"The United States strongly condemns the suicide attack yesterday in Kunar province, Afghanistan, that killed USAID Foreign Service Officer Ragaei Abdelfattah, three ISAF service members and an Afghan civilian, and injured a State Department Foreign Service officer," Secretary of State Hillary Clinton said in a written statement.

"On behalf of President Obama and the American people, I have sent my deepest condolences to Ragaei's family and to the entire U.S. Mission in Afghanistan."

CNN's Samuel Gardner, Greg Morrison and Chelsea J. Carter.