A gunman who opened fire at an air force training centre in Kabul, leaving eight US troops and an American contractor dead, did not appear to have any links to the Taliban, NATO said Saturday.The Afghan ex-pilot involved was shot dead during the incident on Wednesday, which was triggered by a row and was the worst attack of its kind in almost a decade of war. \"At this point in the investigation, it appears that the gunman was acting alone. Beyond that, no Taliban connection with the gunman has been discovered,\" said a NATO release. \"However, the investigation is still ongoing, and we have not conclusively ruled out that possibility,\" it said. The US air trainers\' deaths raise fresh questions over the massive NATO-led effort to expand and train Afghanistan\'s military and police so they can take control of security when foreign combat operations end in 2014. Taliban militants have tried to infiltrate the ranks of the Afghan army and police to carry out attacks against international forces from within, a matter of huge concern for both Afghanistan and its NATO-led military backers.There have been incidents where Afghan army or police recruits have opened fire on NATO troops and caused casualties. However the Air Force attacker\'s motives are not yet known, nor was it clear who killed him. \"Initial ballistics analysis and post-event imagery indicate that the alleged gunman, who appeared to be acting alone, was severely wounded prior to departing the room where the initial attack took place,\" NATO said. The initial findings show that the the gunman \"appeared to be carrying two weapons. The gunman was later found dead at a different location within the building,\" it added. The attacker was a 45-year-old former pilot who had been working as an air force administrator, Colonel Mohammed Bahadur Raeeskhail, the Afghan air force\'s media relations chief said earlier.The Taliban claimed responsibility in a text message to AFP, but are known routinely to exaggerate their claims. An Afghan official, speaking on condition of anonymity, said the gunman was from a well-respected Kabul family and that the shooting was the result of a disagreement, not terrorism. There are around 130,000 international troops serving in Afghanistan, the bulk of them from the United States, although Afghan forces are in control of security in Kabul.