Hamas tightened its grip over the Gaza Strip in fierce street battles with Fatah rivals. Hamas gunmen overran Fatah-linked Palestinian Authority security compounds in northern and southern Gaza on Wednesday, sparking clashes in which at least 22 people were killed. The dead include two unarmed Palestinians who took part in a rally calling for the factions to reconcile, and a Palestinian working for a U.N. relief agency. In the southern town of Rafah, dozens of Fatah militiamen fled the fighting to neighboring Egypt. “What’s happening in Gaza is madness,” said Palestinian Authority President Mahmoud Abbas, the Fatah leader.The United States said the infighting underscored the Palestinian Authority’s inability to come together around a plan for peace with Israel. “Palestinians are going to have to sort out their politics and figure out which pathway they want to pursue, the pathway toward two states living peaceably side by side or whether this sort of chaos is going to become a problem,” said White House spokesman Tony Snow.