A suicide bomber wearing an explosive vest struck a forward operating base in eastern Afghanistan late Wednesday, killing eight American civilians, the U.S. military said.

Eight American civilians were killed according to Lt. Col. Almarah Belk, a Pentagon spokeswoman.

The bomber attacked Forward Operating Base Chapman in Khost province, but another military official speaking on background said the base no longer houses ISAF forces, but has been turned over to “other agencies.”

“We don’t own that outpost anymore,” a second military official said. “It’s not ISAF or [U.S. Forces-Afghanistan]; it’s not a military FOB.”

The official said the base used to house members of the Khost Provincial Reconstruction Team, but it had been turned over to another U.S. agency he was unable to identify.

CNN reported earlier that the suicide bomber walked into either a dining facility or the base gym.

At least 508 coalition soldiers have been killed in Afghanistan this year, including 311 Americans, according to, a Web site that tracks U.S. and allied deaths in Afghanistan and Iraq.

Wednesday’s bombing represents one of the worst breaches of security ever at a foreign base in Afghanistan.

Although Taliban insurgents frequently attack coalition installations with rockets and mortars, and suicide bombers have struck frequently at the perimeter, Wednesday’s attack would represent one of the only known times that a suicide bomber has managed to make into a secure facility.

In December 2004, 14 U.S. soldiers, four U.S. citizens employed by Halliburton and four Iraqi soldiers working with the U.S. military were killed in an attack on a dining hall at Forward Operating Base Marez next to the main U.S. military airfield at Mosul.

According to media reports at the time, 72 other personnel were injured in the attack, carried out by a suicide bomber wearing an explosive vest and the uniform of the Iraqi security services. It was the single deadliest suicide attack on American soldiers during the Iraq war.

Wednesday’s bombing also comes only a day after an Afghan soldier shot and killed a U.S. servicemember and wounded two Italian troops in Badghis province in western Afghanistan.

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