one could call them Egyptian, but I'm thinking it was the Al Qaeda-linked Bedouin group in the Sinai. There is an Egyptian offensive going on against them right now and they probably think it is motivated by Israel and the US...thus, they crossed borders and attacked where they could. Also, it's Ramadan, so they did probably try to target soldiers on the bus. Just my two cents.
47 killed in clashes between ISIS, Syrian rebels near Turkey border, monitor says (Reuters)
from the article: Seven killed in series of terrorist attacks in southern Israel