Three Hamas militants were killed in Gaza during an Israeli airstrike early Saturday morning, fracturing the fragile cease-fire. After two years of relative calm following the Gaza war, Hamas militants began firing scores of rockets into southern Israel through January and February, escalating the attacks in March. On March 19, Hamas fired 54 mortars. The Israeli air force retaliated, then last Wednesday Hamas exploded a bomb at a Jerusalem bus stop, wounding 25, 15 of them seriously. Yesterday a small group of Hamas militants said the new Israeli airstrike freed them to escalate their attacks on Israel. Abu Mujahed, a spkoesman for the group, said, "Our response will be at the same level of the crime." The Israeli military claimed the three militants attacked were members of a Hamas terrorist group that was planning to kidnap Israelis over Passover. Hamas leaders denied the kidnapping role.