Oh, no! Hamas has to deal with terrorism! What a completely unexpected turn of events! The same government that shoots crude missiles at Israeli elementary schools now has to deal with IEDs. They're shocked, shocked! to find terrorists in their midst!
The fighting goes both ways, in any case. The two groups have targeted each other for violence ever since Ismail Haniyeh grabbed power in Gaza. Hamas uses Fatah as an excuse for its own failings, and Fatah attacks Hamas to grab power back. Given that the street soldiers for Fatah mainly belong to the al-Aksa Martyrs Brigade, the conflict mainly represents a turf war between two terrorist groups.
The Israelis and the rest of the world need to maintain Gaza's isolation. Hamas has created a terrorist protostate in Gaza, and Hamas has to live with the consequences. When Gazans get tired of Hamas and Fatah, they will have to get rid of them. Until the terrorism ends, not one American dollar should go to Gaza.