A suicide bomber wearing an Afghan border policeman's uniform blew himself up Thursday at a U.S. base near the Pakistani frontier, wounding five Americans, an Afghan official said.

The spokesman for Paktia province, Roullah Samoun, said the attack occurred after sundown in a barracks at a U.S. facility in the Dand aw Patan district in eastern Afghanistan, about 35 miles east of Gardez.

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He did not identify the base by name or say what kind personnel are stationed there.

U.S. officials confirmed Thursday afternoon that "several" U.S. service members were injured in an explosion at a joint U.S.-Afghan outpost in Paktia but gave no further details.

On Dec. 30 a Jordanian believed to be a double agent blew himself up at a CIA base in another border province, Khost, killing seven agency employees and a Jordanian intelligence officer.

The attack reported Thursday occurred about 400 miles northeast of the Taliban town of Marjah, which is under siege by U.S. and Afghan troops.