Israeli Defense Minister, Ehud Barak, decided last night to seal off all of Gaza's crossings, after they have been partially reopened over the weekend, in response to yesterday's homemade shells fired from Gaza into nearby Israel. Israeli sources said yesterday that Israel considered the firing of homemade shells a 'grave development' in the shadow of a truce deal between Israel and Palestinians, which was reached last Thursday after long Egyptian mediations. The Saraya al-Quds brigades, the armed wing of the Islamic Jihad in Gaza, claimed responsibility for the homemade shells fired, saying it was in response to the Israeli army's assassination of one of the group's leaders in the West Bank on Tuesday morning.  The Islamic Jihad did not sign the truce deal but said it would honor the agreement. Also, the group has its own reservations about the deal, saying it is 'vague' and does not include the West Bank. In a statement faxed to the press, the ruling Hamas party in Gaza called on all Palestinian factions to help make the truce hold as it is in the best interests of the Palestinians. Since the beginning of this week, Israel allowed increased shipments of essential goods and commodities into the coastal territory, after partially easing a one-year-old blockade in honor of the Egyptian-mediated ceasefire agreement.