Accidental discharge

"An 8-year-old Iraqi girl was killed Saturday and several other civilians were wounded when gunfire from an American military convoy struck a crowd of Shiite pilgrims traveling to the holy city of Karbala, witnesses and Iraqi officials said. In a statement on Saturday, the American military said that there had been an accidental discharge of a weapon and that it had reports of two people wounded in Diwaniya, the area in central Iraq where the shooting took place. It said it was starting an investigation, but declined to give any details." Who writes those official military statements? Accidental discharge?