US intelligence officials say yes - it was a Mossad operation carried out at not just any ammunition dump but a base for the sophisticated Shahab missiles. The Shahab 3 is the missile mentioned in the IAEA report that was being sized up for a nuclear warhead by Iranian scientists.

Time Magazine:

The powerful blast or series of blasts - reports described an initial explosion followed by a much larger one - devastated a missile base in the gritty urban sprawl to the west of the Iranian capital. The base housed Shahab missiles, which, at their longest range, can reach Israel. Last week's report from the International Atomic Energy Agency (IAEA) said Iran had experimented with removing the conventional warhead on the Shahab-3 and replacing it with one that would hold a nuclear device. Iran says the explosion was an accident that came while troops were transferring ammunition out of the depot "toward the appropriate site." (See why ties between the U.S. and Iran are under threat.)

The explosion killed at least 17 people, including Major General Hassan Moqqadam, described by Iranian state media as a pioneer in Iranian missile development and the Revolutionary Guard commander in charge of "ensuring self-sufficiency" in armaments, a challenging task in light of international sanctions.

[...]

But the incident also argued, maybe even augured, against an outright strike. If Israel - perhaps in concert with Washington and other allies - can continue to inflict damage to the Iranian nuclear effort through covert actions, the need diminishes for overt, incendiary moves like air strikes. The Stuxnet computer worm bollixed Iran's centrifuges for months, wreaking havoc on the crucial process of uranium enrichment.

What Time doesn't mention is that these are acts of war and if a de facto state of war already exists between Israel and Iran, just about anything can be justified on that basis - including assassinating nuke scientists and sabotaging computer nets.

I would expect more "accidents" like the one over the weekend for the foreseeable future.