By Sara Sidner, Frederik Pleitgen and Chelsea J. Carter
NEAR THE ISRAEL-GAZA BORDER (CNN) – Israel hammered the headquarters of the Hamas-run government in Gaza and rockets soared from Gaza toward Israel, including one that was blocked by a missile defense system as it headed straight to Tel Aviv.
Air raid sirens screamed in Tel Aviv, and Hamas’ military wing claimed responsibility for shelling the city. But the Israel Defense Forces said its Iron Dome missile defense system blocked a Tel Aviv-bound rocket.
Earlier, Israeli warplanes leveled the Palestinian Cabinet building, where on Friday Egyptian Prime Minister Hesham Kandil met with Hamas officials. The strikes hit the office of Prime Minister Ismail Haniyeh, the Hamas Ministry of the Interior and a police compound, Israel and Hamas said.
The conflict took a grim turn Friday after rockets fell near Jerusalem, Israel’s seat of power.
As Palestinian fighters and Israeli soldiers traded fire, Israeli troops and tanks massed near the border of the besieged Palestinian territory Saturday, raising the specter of an imminent ground invasion.
Convoys carrying tens of thousands of Israeli soldiers rolled toward the Gaza border Saturday, part of what the IDF described as 30,000 troops that were being mobilized along the Israeli-Gaza border.
The Israeli government has authorized the call up of 75,000 reservists, the latest move in Israel’s days-old military campaign to stop daily rocket attacks from Gaza.
“We are in the process of expanding the campaign,” Brig. Gen. Yoav Mordechai, an Israel Defense Forces spokesman, told Israel’s Channel 2.
Leaders across the world have called on Israeli and Palestinian governing bodies to show restraint, fearing — at a minimum — a possible repeat of Israel’s 2008 invasion that left at least 1,400 people dead.
Moussa Abu Marzouk said he and other Hamas leaders were in Cairo, meeting with Egyptian President Mohamed Morsy and the country’s intelligence officials to find a solution to the crisis.
Arab League foreign ministers met in an emergency session in the Egyptian capital, and the group’s secretary-general, Nabil ElAraby, denounced Israeli actions, echoing the criticism of Israel from other leaders across the Middle East and Muslim world.
He said the Arab League should re-evaluate and question the benefits the Middle East peace process — which he called “a process without peace.” And, he said, the Arab nations should work to bring the issue front and center to the International community.
A White House spokesman, saying “the precipitating factor for the conflict was the rocket fire coming out of Gaza” into civilian areas, stressed that “Israel has a right to defend itself. He also underscored the importance of Israel avoiding civilian casualties.
“Israel is going to make choices about its own military operations,” said Ben Rhodes, White House deputy national security adviser for strategic communications. “I think there’s a broad preference for de-escalation if it could be achieved in a way that ends that threat to Israeli citizens.”
Eleven people were killed in Israeli airstrikes in Gaza on Saturday, raising to 42 the number killed since Israel’s military operation, dubbed Pillar of Defense, began Wednesday, according to Palestinian government and health officials.
More than 385 in Gaza have been wounded since Wednesday, according to the Palestinian Interior Ministry.
Israel is reporting three deaths from a Hamas rocket attack in the southern community of Kiryat Malachi. There have been at least 18 Israeli injuries, including five civilians and four Israeli soldiers wounded by rocket fire from Gaza, the military said.
More than 400 rockets have hit Israeli territory since Wednesday, the IDF said.
For days, Israel has been using airstrikes to target what it describes as rocket-launching sites operated by Hamas and other militant groups. Israel airstrikes have hit more more than 830 targets in Gaza since the operation began, the IDF said.
The IDF, which describes Hamas-run Gaza as a “front-line base” for its adversary Iran, said it targeted a Hamas base in southern Gaza and two Hamas operatives on Saturday, one in charge of smuggling and an air defense official.
“Overnight, the IDF targeted a terror activity site in the central Gaza Strip, deliberately located and hidden inside a mosque, in the vicinity of a school,” the IDF said, accusing Hamas of using “the Palestinian civilian population as a human shield.”
It was unclear from the statement whether the mosque was targeted in the airstrike. The IDF did not immediately respond to a CNN request for comment, and Palestinian officials did not identify the destruction of a mosque in its latest list of buildings and facilities damaged and destroyed in the Israeli airstrikes.
Palestinian militants, meanwhile, launched a barrage of rockets at southern Israel, including four that hit the coastal community of Ashdod, the IDF said.
One of the rockets hit a house and another landed near a kindergarten, the IDF said. There were no immediate reports of casualties.
The Izzedine Al Qassam Brigades, the Hamas military wing, said its fighters shelled the Zikim military base near Ashkelon and the Israeli cities of Ashdod and Beer Sheva.
Hamas accused Israeli warplanes of hitting an apartment building Saturday in the northern Gaza community of Jabalia Camp, killing at least three people and wounding more than 30, according to Hamas-run al Aqsa TV. Footage broadcast by al-Aqsa showed people clamoring over smoking ruins, searching for survivors.
Palestinians incensed over Israel’s offensive took to the streets in the West Bank, the Palestinian territory, whose government is dominated by the Fatah movement.
Four people were seriously injured in Beitanya near Ramallah when Israeli soldiers fired “high-velocity projectiles” toward demonstrators, Palestinian medical sources said. Seven others were lightly injured by rubber steel-coated bullets and tear gas inhalation, the sources said.
In Bait Omar, demonstrators attempted to march out of the village but were stopped by Israeli soldiers, who fired stun grenades and tear gas.
Fatah and Hamas have been fierce rivals in recent years. Fatah is more moderate on Israel than Hamas, and its leaders have engaged in peace talks with Israel over the years.
CNN’s Sara Sidner reported from Gaza City; CNN’s Kindah Shair reported from Jerusalem; CNN’s Fred Pleitgen reported from southern Israel; CNN’s Chelsea J. Carter, Joe Sterling and Yousuf Basil reported from Atlanta; CNN’s Jessica Yellin, Ben Wedeman, Amir Ahmed and Joe Vaccarello as well as journalists Per Nyberg and Mohamed Fadel Fahmy contributed to this report.