The Pentagon said Thursday it is "deeply concerned" by a rash of attacks in which NATO soldiers have been shot by their supposed allies in the Afghan security force. 

Pentagon spokesman Capt. John Kirby confirmed that "several" U.S. soldiers were injured in Wardak province earlier this week after an Afghan wearing a soldier uniform began shooting at the troops. Officials have said a total of five Americans were shot in the attack -- Kirby said they are in "stable condition," though the attacker "fled the scene and is still at large." 

The attack was just the latest incident where Afghan security forces have targeted NATO trainers and partners.

The number so far this year is quickly approaching the tally for all of 2011. The Pentagon recorded a total of 19 attacks involving 26 deaths, 13 of them American, as of early July. In 2011, according to Kirby, there were 21 attacks and 35 deaths.