ISAF official statement on their website
KABUL, Afghanistan (September 30) – Early this morning, International Security Assistance Force observed what it believed was a group of insurgents attempting to fire mortars at a coalition base in the border area of Dand Patan district, Paktiya Province. An ISAF air weapons team was called to provide fire support and engaged the suspected insurgents' firing position, located inside Afghanistan along the border area. ISAF aircraft did enter into Pakistani airspace briefly as they engaged this initial target.
After the initial strike, the aircraft received what the crews assessed as effective small arms fire from individuals just across the border in Pakistan. Operating in self defense, the ISAF aircraft entered into Pakistani airspace killing several armed individuals.
Subsequently, Pakistan military officials informed ISAF that members of their border forces in the area had been struck by coalition aircraft.