A NATO airstrike killed at least five private security guards Tuesday who were apparently involved in guarding a supply convoy for international troops, Afghan police said. NATO confirmed that an airstrike was called in by forces in Ghazni province in eastern Afghanistan, but it its initial reports suggested the strike was on insurgents. The international coalition said it authorized the strike after its forces observed "suspected insurgents" setting up an ambush site and an air weapons team confirmed the insurgent activity in Gelan district. They later found several machine guns, a rocket-propelled grenade and four AK-47 assault rifles. NATO said there were no reports of a convoy in the area. The alliance had previously said the airstrike was called in by a convoy that was under attack. Afghan officials said there were no insurgents involved.