Army Staff Sgt. Robert Bales, accused of killing Afghan civilians, most of them women and children, in a shooting rampage in Kandahar province last week, will be charged with 17 counts of murder, a U.S. official said Thursday.

The charges signed against Bales include 17 counts of murder, six counts of attempted murder and six counts of aggravated assault as well as dereliction of duty and other violations of military law, the official told the Associated Press on condition of anonymity because the charges had not been announced.

Earlier accounts of the incident, which has damaged U.S.-Afghan relations, had tallied 16 victims, including nine children and three women.

Bales, 38, a four-tour combat veteran, is being held at military detention center in Fort Leavenworth, Kan.

His civilian defense attorney, John Henry Browne of Seattle, was not immediately available for comment.

Earlier this week, Browne said U.S. authorities had no proof of what occurred on the evening in question, and said Bales had no memory of the incident.

The charges are to be read to Bales Friday. He faces trial under the Uniform Code of Military Justice.

Legal proceedings would likely take place at Bales' home base, Joint Base Lewis-McChord outside Tacoma, Wash., the U.S. official told Reuters.

Bales' wife, Karilyn, and their children, are being sheltered by the Army at Lewis-McChord.