An Afghan army soldier killed at least one NATO soldier Saturday, near the southern Afghan city of Lashkar Gah, due this week to be one of the first places where NATO will hand security control to Afghan forces, a senior police source said. "The shooting happened during a joint security patrol," said the senior police detective, who asked not to be named as he was not authorised to speak to the media. The NATO-led International Security Assistance Force said it was investigating an incident in southern Afghanistan.