Afghan authorities said Friday they were investigating an overnight raid by NATO troops on a private security company that killed two Afghan guards in an operation that NATO said was conducted following a threat against the U.S. Embassy. Interior Ministry spokesman Zemeri Bashary said the probe was looking into why international forces raided the compound of Tiger International, an Afghan private security company, killing two Afghan guards and wounding another two, according to AP. But NATO said the operation was conducted jointly with Afghan forces after receiving «a credible threat to attack the U.S. Embassy.» It said coalition forces «coordinated with Afghan security forces» and moved into an area where intelligence reports had located two vehicles thought to be loaded with explosives. The coalition forces were fired on after they had announced their arrival, and they returned fire, killing two of the shooters, NATO's statement said. Two others were wounded, it said, and 15 people were detained in the operation. The detained were released after a senior Afghan army official arrived and «personally vouched» for them, NATO said. A large amount of weapons was also seized. However, Kabul criminal investigation chief Mohammad Zahir insisted there had been no coordination with Afghan authorities before the raid, and that the Afghan guards had not opened fire on the coalition troops. He said the only arms seized were several weapons belonging to the security guards. Defense Ministry spokesman Gen. Mohammad Zahir Azimi said his ministry was not aware of the operation either. The incident comes after two cases this week in which NATO forces killed Afghan civilians, either during a battle with insurgents or after acting on intelligence relating to suspected militants. The issue of night raids and civilians killed during operations is particularly troubling for NATO and the Afghan government, and the international coalition says it is careful to avoid such casualties.