Attiqullah Khan, district chief of Gerda Sarai, confirmed the attack but like Samon, he had no more details.
Three American soldiers were killed by an Afghan soldier on Sept. 21 in Paktia.
Killings by uniformed Afghans of foreign soldiers and civilians rose dramatically last year, eroding confidence between the sides at a crucial turning point in the conflict. So-called insider attacks killed 62 personnel in 47 incidents last year, compared to 35 killed in 21 attacks a year earlier, according to NATO.
So far in 2013, 12 foreign soldiers have been killed in eight such attacks, including Thursday's, according to an Associated Press count.
In some cases, militants have donned Afghan army or police uniforms to attack foreign troops, but a number have been carried out by members of Afghan security forces against their own comrades.
The attacks come as NATO and Afghan forces are working more closely, with foreign troops handing over security to the Afghans and continuing to train them prior to an almost total withdrawal by the end of 2014.