By KARIN LAUB and IBRAHIM BARZAK -- The Associated Press
GAZA CITY, Gaza Strip (AP) -- Israeli airstrikes killed three Palestinian civilians and two militants in the Gaza Strip on Monday and Palestinian rocket squads barraged southern Israel in escalating fighting that defied international truce efforts.
A high school student, a father and daughter were among the dead.
The cross-border violence, touched off by Israel's killing of a top Palestinian militant leader on Friday, has been the worst exchange of fire between Israel and the Hamas-ruled territory in months.
The fighting has so far killed 23 Gazans, including 18 militants, seriously wounded two Israelis, and disrupted the lives of 1 million Israelis living within the range of Gaza rockets.
At a news conference in Gaza City on Monday, masked members of Islamic Jihad's military wing demanded Israel cease fire first and stop targeting militants.
"We warn the leaders of the enemy of the consequences of testing our patience. Our patience is limited and shall be turned into fire and destruction upon them," one of the masked men said.
Chief military spokesman Brig. Gen. Yoav Mordechai said Israel would halt its raids if the rocket fire stopped, but added that the Israeli military would continue to take pre-emptive action to foil militant attack plans.
Prime Minister Benjamin Netanyahu warned that Israel would expand its offensive if needed to stop the Palestinian rocket attacks.
Speaking at a meeting of his Likud party Monday afternoon, Netanyahu said the military "is ready to broaden its operations and will continue to act as necessary." He did not elaborate.
Israel said it launched Friday's initial airstrike to stop a militant group's plan to infiltrate into Israel through Egypt's Sinai peninsula. In the past, similar flare-ups have died out by themselves or with informal cease-fires negotiated by third parties, often Egypt.
In this case too, Egypt has been trying to mediate an end to the clashes, and Hamas has also appealed to other Mideast countries to join the truce attempts. But by Monday afternoon, there was no sign of progress.
On Monday, Israeli aircraft swooped down on Gaza 11 times by midday, striking what the military said were rocket-launching sites and a weapons storage facility. Two militants, a 16-year-old high school student, and a 65-year-old man and his 30-year-old daughter were killed in four separate raids, Gaza health official Adham Abu Salmia said.
One of the militants was killed while riding a motorcycle. The teenager died while walking to school, and the father and daughter were killed when a missile struck right outside their home, witnesses said.
The Israeli military said the air attacks were in response to continued rocket fire. Police spokesman Micky Rosenfeld said more than two dozen rockets had struck southern Israel by early Monday afternoon. One damaged a preschool building on a communal farm shortly before children were scheduled to arrive, but no one was hurt, Rosenfeld said.
Schools in the area were closed for a second day to avoid casualties, keeping tens of thousands of children at home. A day earlier, a rocket struck the courtyard of one of the empty schools.
Also Monday, militants fired three mortar shells into Kerem Shalom, the sole cargo crossing between Israel and Gaza through which 70 percent of all goods that enter the Palestinian territory pass. Two vehicles were hit on the Palestinian side of the crossing, but no one was injured, Israeli officials said and work resumed after a brief halt.
Israel says the newly introduced Iron Dome missile defense system intercepted dozens of the more than 190 rockets fired since the clashes erupted, and military officials suggested this averted more casualties and damage.
"The vast majority of the rockets shot at Israeli cities were intercepted," said Brig. Gen. Doron Gavish, commander of the defense unit that includes Iron Dome. "This is a new era in military history, there is an effective defense against rockets."
Although military officials are quick to note that Iron Dome will not offer hermetic protection, its success rate raised hopes the military has found a way to rob militants of their most potent weapon -- primitive, short-range rockets that have made life miserable for hundreds of thousands of Israelis by eluding their high-tech military for years.
Israeli Foreign Minister Avigdor Lieberman warned Monday that the continued fire from Gaza "buries any chance of a territorial link between Gaza and the West Bank." The Palestinians want both areas, which lie on opposite sides of Israel, for a future state, along with Israeli-occupied east Jerusalem.
Gaza and the West Bank are today ruled by dueling governments. Hamas is internationally shunned because of its refusal to renounce violence against Israel, and Israel's peace talks with the West Bank government of Palestinian President Mahmoud Abbas stalled years ago.
Although the current fighting shows no signs of subsiding soon, both Hamas and Israel seem eager to avoid the kind of all-out war they waged three years ago.
As it has done since that conflict, Hamas has stayed out of the current clashes for fear of provoking a harsh Israeli retaliation. But that has not stopped other, smaller Gaza factions from attacking Israel, and Israel continues to hold Hamas ultimately responsible for any violence emanating from Gaza.
Egyptian truce efforts appeared to stall, as both sides said they were willing to keep fighting.
Israeli Prime Minister Benjamin Netanyahu warned that Israel would keep striking those trying to harm Israeli civilians and that Israel is "ready to broaden its operation."
Gaza militants insisted that Israel stop firing first and that it promise to halt airstrikes aimed at killing Gaza militants for good, a guarantee Israel is unlikely to give. Egypt sided with the Palestinians in their demands.
In Israel, government officials and missile experts praised the performance of Iron Dome, an Israeli-made system designed to shoot down short-range rockets like those fired from Gaza.
Iron Dome has been rolled out over the past year, and the current fighting poses its most serious test. Israel has other systems deployed against longer-range missiles.
Iron Dome uses cameras and radar to track incoming rockets and intercepts only those that would pose a threat to people and property, ignoring those that are expected to fall in open areas.
The military said that of 143 rockets fired since Friday, it tried to intercept 63 and succeeded in all but nine of those attempts. No Israelis have been killed in the current fighting, and property damage has been relatively minor.
Uzi Rubin, a missile expert and former Defense Ministry official, said Iron Dome has exceeded expectations. "The performance up to now has been almost flawless," Rubin said, adding that the perception could change quickly in the event of casualties.
Military analyst Yiftah Shapir said Iron Dome would likely score fewer interceptions if Israel were attacked by a larger number of missiles simultaneously, a scenario Israel would have to consider if it attacks Iran over its nuclear program. Tehran's proxies on Israel's borders - the Lebanese Hezbollah militia, along with Hamas and Islamic Jihad in Gaza - are believed to have a stockpile of tens of thousands of rockets and missiles.
Shapir said Iron Dome has given a psychological boost to those living in rocket range, but it has not reduced the economic damage caused by closing schools and keeping hundreds of thousands of people from their jobs and daily routines.
Others noted that each intercept costs about $100,000, arguing that the cost could be prohibitive if Israel were fighting a full-fledged war.
In the current round, Islamic Jihad, the second largest militant group in Gaza, has taken the initiative.
Islamic Jihad has maintained close ties to its sole sponsor, Iran, while Hamas in recent months has drifted away from its longtime patron, in part because of disagreements over Syria's brutal crackdown on regime opponents. Iran has punished Hamas for refusing to side with Syrian President Bashar Assad, including by cutting funding.
Israeli officials believe that Islamic Jihad has amassed hundreds of rockets and missiles, if not thousands, including weapons taken from Libyan military bases during the chaos surrounding the fall of Libya's longtime ruler, Moammar Gadhafi. Missiles and other weapons reach Gaza through smuggling tunnels running under its border with Egypt.
In the current round, Islamic Jihad showed that the three main cities in southern Israel - Ashkelon, Ashdod and Beersheba - are in easy reach of its Russian-designed Grad rockets. On Monday, two dozen rockets struck southern Israel, including one that damaged an empty preschool on a communal farm. Police said no one was hurt.
Rubin believes Islamic Jihad also has longer-range missiles that could reach the major population centers of central Israel, like Tel Aviv. Hinting at possible escalation, Islamic Jihad warned Monday that its "patience is limited" and that it is ready to unleash "fire and destruction," though such rhetoric is routine during flare-ups like this one.
Hamas, which has ruled Gaza since a 2007 takeover, has pointedly kept out of the fighting and is appealing for calm, though it has not prevented rocket fire by Islamic Jihad and the Popular Resistance Committees.
Hamas is trying not to provoke a major Israeli offensive that could undermine its control of the territory of 1.7 million Palestinians. An Israeli offensive three years ago delivered a damaging blow.
"Hamas is behaving like a responsible government in Gaza," said Fawaz Gerges of the London School of Economics.
On Monday, four militants, a 16-year-old, a 65-year-old man and the man's 30-year-old daughter were killed in four separate raids, Gaza health official Adham Abu Salmia said.
The teenager died while walking to school, and the father and daughter were killed when a missile struck outside their home, witnesses said. Two dozen Palestinians, including several children, were wounded in a separate pre-dawn strike. Israel said the raid targeted munitions stores in a residential building.
In Israel, thousands spent another day in bomb shelters, while others ran for cover when sirens wailed. Some 200,000 students were kept home from schools for a second day.
The Maariv daily ran a front page picture of a 10-year-old girl from Beersheba, shown lying on a street with her hands over her head. She later explained that a siren had just gone off, and she dropped to the ground because she didn't have anywhere to run.
Barzak reported from Gaza City, Gaza Strip. Additional reporting by Ian Deitch in Jerusalem.