The new commander of U.S. and NATO forces in Afghanistan has apologized to the people of Kunduz for the deadly attack on a hospital in the city last year that killed 42 people.

U.S. Army Gen. John Nicholson traveled Tuesday to the northern city to meet local leaders and relatives of those who died in the Oct. 3 attack.

A U.S. Air Force AC-130 gunship attacked the hospital run by medical charity Doctors Without Borders in what Nicholson called a "horrible tragedy."

More than a dozen U.S. military personnel have been disciplined for mistakes that led to the sustained attack. A U.S military report on the hospital attack is expected to be released within days.

Nicholson's wife Norine accompanied him to Kunduz, along with acting defense minister Masoom Stanekzai.