According to news reports, some 28 Palestinians were killed and more than 120 were wounded in Gaza last weekend as Hamas attacked a rival Islamist group, Jund Ansar Allah. On Friday, the group's leader, who had been told to turn over his mosque to Hamas' control, instead declared the establishment of an Islamic emirate in Palestine. In retrospect, he seems to have spoken too soon.
There are a number of other Islamist groups in Gaza; for an in-depth analysis of the currents and counter-currents, see this MEMRI analysis. Palestinians in Gaza who simply yearn for a normal life are in big trouble as long as these guys are competing for control.