The report seems to indicate that it may be something to do with escalating tension between Israel and Hezbollah.
Doubtful. As in the Texas City Disaster, the explosion was from ammonium nitrate fertilizer, which, if stored in massive quantities can explode. Unless properly mixed with an accelerant, it's unreliable, even treacherous. Often, the same storage/handling procedures that always went well, would suddenly cause a catastrophic blast.
It's a very useful explosive, because it has a low brisiance, meaning it tends to "push" rather than shatter. The explosion is not a detonation. So it's used a lot in blasting rock cuts for highways. If you've ever noticed vertical grooves in such cuts, that's where holes packed with ammonium nitrate and diesel fuel were exploded. Instead of blowing hunks of rock everywhere, the explosion tends to just push the rock away in nice, manageable piles.
But huge quantities are super dangerous, unless carefully stored.
Texas City disaster - Wikipedia
A few years ago, a similar blast in West, Texas, flattened a facility and numerous nearby structures, killing a number of people, including firemen who were trying to put out the fire that eventually caused the explosion.