The death toll is mounting on both sides after a weekend of cross-border violence between Israel and militants on the Gaza strip.
The most intense clashes in years have so far left at least four Israelis and 23 Palestinians dead.
The Israeli army says more than 600 rockets have been fired into Israeli territory since Saturday. They say more than 150 have been intercepted.
Parts of the international community, including the UN, have called for calm.
Reports on Sunday night suggest the UN, Qatar and Egypt are trying to broker a ceasefire.
The Israeli military say they have hit 320 targets so far this weekend.
On Sunday, Israeli Prime Minister Benjamin Netanyahu said he had ordered the military to “continue its massive strikes on terror elements” in Gaza.
Israeli forces around the strip would be “stepped up with tank, artillery and infantry forces”, he added.
As rockets continue to fall in Israel, all schools within 40km (25 miles) of the Gaza strip have been closed and some shelters have opened to the public.
What do we know about casualties?
Four people have so far died from the violence in Israel:
- A 58-year-old died from injuries in a rocket strike on a house in Ashkelon on Saturday night
- Another died in Ashkelon on Sunday when a rocket hit a factory
- Another man, 67, was killed when his car was apparently struck by an anti-tank missile
- A fourth, who was in his early 20s, was killed in the southern city of Ashdod
The Gaza Health Ministry says 23 Palestinians have died across the weekend. Most of the deaths came on Sunday. The Islamic Jihad group said seven of the dead were its members.
Civilians, including a 12-year-old boy and two pregnant women were also among those reportedly killed.
Israel has contested the account of the death of one woman and her 14-month-old niece on Saturday. They blamed their deaths on a Palestinian rocket that fell short of its target.
On Sunday, the Israeli military admitted a targeted assassination of a Hamas commander named Hamed Hamdan al-Khodari – sharing a video of the apparent moment they hit his car.
The sites Israel says has destroyed include a multi-storey building in Gaza City, which it said included Hamas intelligence offices.
Turkey said its state news agency Anadolu had an office there. Foreign Minister Mevlut Cavusoglu called Israeli strikes on civilians “a crime against humanity”.
On Sunday night, Hamas leader Ismail Haniya said in a statement that “returning to a state of calm is possible” if Israel committed to a “complete ceasefire”.
How did the latest violence develop?
It began on Friday, during protests in Gaza against the blockade of the area – which Israel says is needed to stop weapons reaching militants.
A Palestinian gunman shot and wounded two Israeli soldiers at the boundary fence. Israel retaliated with an air strike that killed two militants.
The rocket barrage from Gaza began on Saturday morning. Israel’s Iron Dome missile defence system shot down dozens of the rockets, but a number of homes in Israeli towns and villages were hit.
How does the flare-up in violence compare?
It is the one of the most surges in violence since the conflict of July and August 2014.
In that year, Israel launched a ground offensive on Gaza following the kidnapping and killing of three Israeli teenagers.
The conflict resulted in the death of 67 Israeli soldiers. Hamas and its allies launched more than 4,500 rocket strikes that killed six civilians in Israel.
On the Palestinian side, 2,251 people, including 1,462 civilians, were killed in the seven-week conflict, according to the UN.
Since then, Palestinian militants have continued to carry out sporadic strikes on Israel.
In a previous wave this year, in March, several rockets were fired into southern Israel, triggering raids on Gaza by the Israeli air force. No fatalities were reported on either side.
In early April a ceasefire was brokered by Egypt, but Hamas and allied militant groups later accused Israel of violating its terms.
What has the reaction been?
Nickolay Mladenov, the UN Special Coordinator for the Middle East Peace Process, has condemned the recent violence and said the UN is working with both sides to calm the violence.
In a statement, UN Chief Antonio Guterres has condemned “in the strongest terms” rockets being launched into Israel.
“He urges all parties to exercise maximum restraint, immediately de-escalate and return to the understandings of the past few months,” the statement added.
Speaking on Fox News on Sunday, US Secretary of State Mike Pompeo said Israelis have “every right to defend themselves” from rocket attacks.
“I hope we can return to the ceasefire that had been in place for weeks and had been holding significantly before this,” he added.
The European Union on Sunday called for rocket fire to “stop immediately”.
Iran’s foreign minister, condemned what he labelled as Israel’s “savage” attacks on Gaza, while also hitting out at “unlimited American support” of Israel.
Save the Children has said it has had to suspend all but essential programs in the Gaza strip.
Jeremy Stoner, their Middle East Regional Director, said the group were “deeply alarmed” by rapidly rising casualties on both sides, and called for de-escalation.