A five-month-old cease-fire between Israel and the armed Hamas movement in the Gaza Strip has been strained by 10 days of violence, and residents are warning of a humanitarian crisis because Israel has sealed the territory's borders.

Israeli forces and Palestinian fighters have clashed repeatedly since early this month, leaving at least 10 Hamas gunmen dead. The United Nations said Friday that it had closed its food-distribution program because it cannot resupply its warehouses and that 750,000 Palestinians who depend on UN aid will have to wait until Israel lets more food enter the strip.

Gaza's main power plant also ran out of fuel because of the closure, and UN and other aid officials warned of mounting problems.