From Zvi, commenting on the article that claimed that many "work accidents" in Gaza were really from infighting:
Gaza is controlled by one vicious terrorist gang, but there are other, equally vicious criminal and terrorist gangs running around. These people have no concern whatsoever for the welfare of Gazans. They focus either on profit, or on serving their foreign masters, or both.
The Army of Islam, which held Alan Johnston hostage and which Hamas violently crushed thereafter, was an example. These people are mostly members of the Doghmush clan, a Turkish criminal family that moved to Gaza in the 1920s. (Incidentally, by what right are a bunch of criminals from Turkey in Gaza at all, and exactly how can they, of all people, justify attacks on Israel? But they are not at all unique. There are many Palestinians who actually hail from other places. It's one of those elephants standing around in the room, which everybody pretends do not exist).
In addition, smuggling tunnels are often controlled by smuggling gangs (though some seem to be controlled by "legitimate businessmen"). In the past, when Gazans have attacked the border crossings with mortars, the culprits have sometimes been identified as smuggling gangs. The attackers were attempting to force closures; by cutting off the flow of aid and trade goods being imported legitimately through the crossings, they hoped to raise the prices that would be paid for their smuggled goods.
With criminal gangs involved in the tunneling business, it is quite reasonable to expect the competition between tunnel operators to turn violent.
Hamas is the ruling gang. It has used either intimidation or violence to suppress political opponents, a number of jihadi groups and also a number of gangs. Some of the incidents have been large and well-publicized (the violent coup against Fatah, the violent suppression of the Army of Islam, the extermination of the al Qaeda group that holed up in the mosque, and so on) but some of them have received little media attention.
Hamas has won itself some friends by being the strong guy in Gaza, but by killing people, it has won itself enemies, too.
And Hamas taught its enemies well. It rose to power in part by carrying out terror bombings and assassinations against Fatah and its supporters. I rather think that others - especially Fatah supporters - would like to do the same to it, though Hamas is not the eternally disorganized and inept rabble that was Fatah, and it seems unlikely that such tactics will make much of a difference against Hamas. The significance of Cast Lead was not lost on many Gazans; Hamas forces proved themselves to be rather worthless in real combat. There are enough crazy idiots on the Fatah side who see the Hamas coup as a stain on their honor, and we all know what that means...