Iraqi police also reported the deaths of six Iraqis after a US Apache helicopter struck two checkpoints near the central city of Samarra. Two Iraqis were wounded during the attacks.
Abu Faruq, leader of an "Awakening" Council unit allied with the US against al-Qaeda, said the six Iraqis were members of his group who had been manning the checkpoints when they came under attack.
"At 5am today, I got a call from the Awakening fighters to say that a helicopter had fired flares above their checkpoint and had then launched an attack," Abu Faruq said.
He said the Awakening Council fighters were wearing reflective vests which distinguished them as anti-al-Qaeda fighters.
A police officer, speaking on condition of anonymity, said the two checkpoints were about 100m apart.
The airstrikes came about two hours after US soldiers stopped at the two checkpoints to meet with the fighters, according to a local leader.
However, the US military said that the aerial attack had been launched after five people "were spotted conducting suspicious terrorist activity," in an area known for roadside bomb attacks.
Abu Faruq said he accompanied police and ambulances when they transported casualties to a nearby hospital, leaving behind the checkpoints covered in body parts, mixed with gravel and bloody clothing.
Awakening groups which comprise mainly of Sunni Arabs were set up by the US military across Iraq.
US military commanders have credited those groups as having been a key factor in the reduction of violence since last June.