The Gaza Strip's four main universities have shut down, saying students can't get to class because of fuel shortages created by Israeli cutbacks. Israel is Gaza's sole fuel provider. In recent months, it has reduced supplies to try to pressure Palestinian militants to halt their rocket fire into southern Israel. The shortages were aggravated last week by two developments. Gaza fuel distributors stopped selling the reduced amounts that did arrive in Gaza, to protest the Israeli cutbacks. Then Israel cut off all supplies after gunmen attacked the Israeli terminal that pumps the fuel to Gaza, killing two workers. Israeli security officials blamed the shortage on Hamas, for refusing to pick up hundreds of thousands of fuel.