It is safe to limit the suspects to eather Hamas, Hizbullah, Islamic Jihad, or ElQaeda. I can't see any other suspects in Sinai who would have the interest to harm Israelies, and harm Egyptian who don't belive in Global Jihad. I am pretty sure Egypt will take this matter real serious.
Poland's central bank head calls story of Nazi train find a hoax (Reuters)
from the article: Netanyahu: Hamas responsible for rockets on Eilat; we will retaliate