According to KIRO TV may be two containers. Their story is confusing -- http://www.kirotv.com/index.html says 2. But the story only references one.
http://www.king5.com/localnews/stories/NW_081606WABterminal18EL.6e187a5.html
Two suspect containers.
See my post 32. The Port worker said 2 containers.