At least a dozen Afghan security forces were killed in a U.S. airstrike during intense fighting with the Taliban at the outskirts of Kabul, Afghan officials said on Tuesday, reviving debate over the accuracy of U.S. airstrikes in the war-ravaged country.

The incident took place in the district center of Logar province, about 50 miles south of Kabul, late on Monday, officials said. Shamshad Larawi, a spokesman for the provincial governor, said that American airstrikes, because of misunderstanding, targeted an Afghan police outpost.

Larawi did not specify the number of casualties but members of the provincial council in Logar said the strike had killed 12 Afghan security personnel, media outlets reported. However, some eye witnesses put the figure at 19 dead, including 17 Afghan police officials and two civilians.

Lt. Col. Martin O’Donnell, a spokesman for U.S. forces in Afghanistan, confirmed that the strike had been carried out and said the killing of Afghan forces was being investigated.

In the first half of this year, U.S. forces dropped nearly 3,000 bombs across Afghanistan, almost double the number for the same period last year and more than five times the number for the first half of 2016, according to officials.

The UN mission in Afghanistan has documented 149 civilians killed and 204 injured by airstrikes in the first six months of this year, a 52 percent increase from the same period last year.