According to Al Jazeera, 18 of the killed are militants (and not 2). From the 5 others, 2 died in the blasts that, according to IAF, are not from Israel. So, though I agree with you that rejoicing on the number of killed (even killed enemies) is a bad thing, the situation is quite different from what you say.
U.S. sanctions Russia's state-owned arms exporter Rosoboronexport (Reuters)
from the article: This round will likely go to Israel