Gaza Prime Minister Ismail Haniyeh said Sunday that Palestinian factions in the coastal strip had responded positively to his contacts with Egypt to halt escalating violence between Gaza and Israel. Egypt is \"working around the clock\" to halt the fighting, Haniyeh said. Israeli airstrikes have killed 18 Palestinians in the Gaza Strip since Friday, including a 12-year-old boy. Militant groups allied to factions other than Hamas have fired dozens of rockets into southern Israel, injuring four Israelis. The Gaza premier said the factions position is \"positive and responsible\" after he made contact with Egypt to end the fighting. A statement from his office said the Palestinian people are \"unbreakable\", and called on Israel to stop the assaults immediately. The Egyptian ambassador to the Palestinian Authority said Sunday that his country was in touch with both sides to halt hostilities. Yasser Othman told Ma\'an that Israel\'s offensive is \"unjustifiable, and a breach to the truce sponsored by Egypt.\" Hamas spokesman Fawzi Barhoum indicated the movement is disapointed with international efforts to stop the fighting. He said in a statement later Sunday that the movement views the response from the Arab and international world to be unequal to Israel\'s violations. Israel started the current fighting, and is responsible to end it, he added.