Aang has totally killed people before. In the avatar-state he killed Commander Zhao at the end of season 1.
Actually that was the Ocean Spirit, acting entirely on its own, after having separated itself from Aang. It drops him off before going after Zhao.
Although, it does seem kinda unlikely that no one died when they were still merged and taking out the Fire Navy fleet...
Edited by Kil, 21 July 2008 - 09:50 PM.