JERUSALEM - Militants in Hamas-ruled Gaza bombarded southern Israel with rockets Thursday and Israel pounded back with air and ground fire, the latest spate of violence that has pushed peace efforts to the sidelines.
Israeli Prime Minister Ehud Olmert vowed to keep striking against what he called the "intolerable" assaults on southern Israel.
Twenty-five Palestinians, including the son of Gaza's Hamas strongman, have been killed since the violence escalated Tuesday. Most were militants but a 12-year-old boy was also killed in a bungled Israeli airstrike, along with his father and uncle.
A foreign volunteer on an Israeli border farm was killed by a Hamas sniper.
Hamas, the Islamic militant group that rejects Israel's right to exist, has intensified its direct involvement in the assaults on Israel since the clashes heated up. The group, which had let other militant factions take the lead in attacking Israel since wresting control of Gaza in June, claimed it fired 36 rockets by midday Thursday, after launching 79 rockets and mortars on Wednesday.
Other groups said they fired four additional rockets and eight mortar rounds.
Israel said at least 23 rockets and two mortars were fired at Israel by late afternoon. One rocket slammed into the side of a house, slightly injuring two people, police said.
Israel struck back at northern Gaza from the air and ground, targeting rocket squads and areas that militants frequently use to fire projectiles. A leader of the small, Hamas-allied Popular Resistance Committees, Raad Abu el-Foul, and his wife, Amnah, were killed when a missile fired from the air hit their white sedan, the faction said.
The group swiftly vowed retaliation.
"Sooner or later, (we) will, by God, avenge every drop of blood shed, and the response will be equal to the crime," it said in a statement.
On Thursday, Olmert acknowledged there was "no magic formula" to stop the militant attacks, but said Israel would not stand for the relentless rocket fire.
"We will continue to fight the (Islamic) Jihad, Hamas and all their allies without compromise, without concessions and without mercy," he told a business conference in Tel Aviv.
Earlier in the week, however, Olmert suggested that Israel would not embark upon a broad military operation in the coastal strip. Past large-scale strikes against Gaza militants have caused heavy Palestinian casualties without halting the rockets.
Militants have launched some 4,000 crude rockets and mortar rounds at southern Israel since Israel evacuated Gaza in the summer of 2005 after a 38-year occupation. The rockets have killed 12 people since 2001 and sown panic in border areas, where people are frequently forced to rush to take cover when sirens alert them to incoming projectiles.
Militants have been extending their reach as well, with one Iranian-made rocket recently traveling some 10 miles inside Israel's borders.
So far, Israel has been largely powerless against the crude, low-flying rockets that stay in the air only briefly. It is in the process of developing a rocket defense system that critics say will be extremely expensive to use.
Hamas' supreme leader, speaking from his base in Syria, said Wednesday that the Israeli raids made the group less likely to negotiate any truce. Khaled Mashaal also said the military action would hurt chances of Hamas' release of Cpl. Gilad Shalit, an Israeli soldier it captured in 2006.
The widening violence has clouded the resumption of Israeli-Palestinian peace talks. On Wednesday, Palestinian President Mahmoud Abbas, Hamas' bitter rival and Israel's moderate partner in newly resumed talks, denounced what he called the Israeli "massacre" in Gaza.
He also took the extraordinary step of calling his foe Mahmoud Zahar, Gaza's most powerful Hamas leader, to express condolences for his son's death in a clash with Israel on Tuesday. Shortly after his son was killed, Zahar accused Abbas of complicity by negotiating with Israel.
In Jordan on Thursday, parliament's lower house denounced the "continuous Israeli attacks on the Palestinian territories," the official Petra news agency reported.
