Israel briefly deployed ground troops inside the Gaza Strip for the first time early Sunday as its military warned northern Gaza residents to evacuate their homes, part of a widening offensive that began against Hamas last week.
Neither Israel nor Palestinian militants show signs of agreeing to a cease-fire, despite calls by the United Nations Security Council and others to end the increasingly bloody six-day offensive that has claimed at least 160 Palestinian lives.
Several Israelis have been wounded in the rocket attacks, but there have been no fatalities.
With Israel massing tanks and soldiers at Gaza's borders, some fear that could signal a wider ground offensive that would cause heavy casualties.
Officials said Israeli commandos targeted a rocket-launching site Sunday during the brief raid. Authorities said four Israeli soldiers were slightly wounded during an exchange of gunfire with Palestinian fighters.
Israel also continued its airstrikes, targeting areas across Gaza early Sunday, ignoring international appeals for a cease-fire as the conflict entered its sixth day.
“We don't know when the operation will end,” Israeli Prime Minister Benjamin Netanyahu told a Cabinet meeting Sunday. “It might take a long time.”
An Israel strike overnight flattened the home of the Gaza police chief, killing at least 18 people in the deadliest attack since Israel launched its offensive on Gaza Tuesday.
The strike also badly damaged a nearby mosque, wounding scores of people. Some worshippers are still believed to be trapped in the rubble.
An earlier airstrike Saturday also hit a mosque. Israeli Defense Forces spokesperson Lieutenant Libby Weiss said the building was being used by Hamas militants.
"It's important to note that this was a mosque that was used almost entirely for Hamas operations. Meaning as a structure perhaps, yes it was a mosque, but it was very clear that it was being used, and I would say almost hijacked by Hamas for terror purposes," Weiss said.
The United Nations humanitarian affairs office has said the majority of Palestinians killed in Israeli strikes since operations began have been civilians.
Several Israeli citizens have been wounded by Palestinian rockets, which are being launched at longer range than in previous conflicts. Israeli defense forces credit their Iron Dome missile defense system, which intercepts rockets in mid-air, with preventing greater casualties.
Netanyahu said Friday Israel is considering all military options despite international calls for a cease-fire.
On Sunday, Netanyahu blamed Hamas for the ongoing military offensive in the Gaza Strip, saying responsibility for any casualties lies with the Palestinian militants.
Israel also accuses Hamas of using Gaza's civilians as human shields by firing rockets from there.
Netanyahu went on to blame Iran for funding, arming and training Hamas, saying that the meeting in Vienna on Iran's nuclear program must prevent the Iranians from developing a nuclear weapon.
If they fail to do so, Netanyahu said, "What is happening around here and what is happening in the Middle East, will be several times worse or maybe beyond that."
Britain, France and Turkey have expressed concerns about the loss of life in Gaza. U.S. President Barack Obama said the U.S. is willing to help facilitate a cessation of hostilities, while backing "Israel's right to defend itself.
Dr. Mahdi Abdul Hadi, head of a Palestinian academic society in Jerusalem (PASSIA), said both Israeli and Palestinian leadership have shown little willingness to back down.
"Netanyahu is refusing any reconciliation, any negotiations, any halting of the operations and he is carrying on the mission as usual," Hadi said. "The same thing, Hamas is going forward as planned, saying whatever will happen will happen to all of us."
Israel claims to have hit more than 1,100 targets inside Gaza since operations began. The military has called up more than 30,000 reservists and is now weighing whether to begin ground operations in Gaza.
German Foreign Minister Frank-Walter Steinmeier will travel to the Middle East on Monday, a foreign ministry spokeswoman said, where he will meet Netanyahu and Palestinian President Mahmoud Abbas, German media reported.
Steinmeier called for an end to “Hamas rocket terror,” in comments to newspaper Bild am Sonntag published on Sunday, and urged a “coalition of reason” to stop the conflict escalating.
UN calls for cease-fire
The U.N. Security Council called for a cease-fire in the Israeli-Palestinian conflict.
In a statement Saturday, the 15-member council called for a de-escalation of the violence, a restoration of calm, and a reinstitution of a 2012 Egyptian-brokered cease-fire between the two sides.
This is the first official response to the crisis by the powerful U.N. body, which has been divided on the Israeli-Palestinian conflict.
Palestinian officials say the death toll from Israel's offensive has risen to about 160, with Israel continuing to strike sites believed to be strategic to Hamas and other militant groups.
WATCH: Gaza Fighting Takes Civilian Toll - report by Zlatica Hoke
Gabe Jaselow contributed to this report from Jerusalem. Some information for this report comes from AP, AFP and Reuters.